Friction MCQ Class 8. Test your knowledge on friction with 100 questions. Learn about static, sliding, rolling friction, lubrication, and its role in everyday phenomena.
Friction MCQ Class 8 Topics:
Introduction to Friction and Measurement: MCQ 1–10
Factors Affecting Friction: MCQ 11–21
Types of Friction: Static and Sliding: MCQ 22–30
Importance and Disadvantages of Friction: MCQ 31–40
Increasing Friction: MCQ 41–45
Reducing Friction (Lubrication and Methods): MCQ 46–60
Rolling Friction: MCQ 61–70
Ball Bearings: MCQ 71–75
Fluid Friction (Drag) and Streamlining: MCQ 76–90
B. A force that opposes motion between two surfaces in contact
C. A force that causes objects to float in water
D. A force that makes objects heavier
B. A force that opposes motion between two surfaces in contact. This is the basic definition of friction.
Question 2: Which of the following is an example of friction in action?
A. A bird flying in the sky
B. A fish swimming in a lake
C. A ball rolling on the ground and slowing down
D. A plant growing towards the sunlight
C. A ball rolling on the ground and slowing down. Friction acts against the ball’s motion, causing it to slow down and eventually stop.
Question 3: What do you call the force that opposes the motion of a book sliding across a table?
A. Gravity
B. Magnetism
C. Friction
D. Inertia
C. Friction. Friction is the force that resists the sliding motion of the book.
Question 4: Imagine pushing a toy car across a carpet. Which force is working against the car’s movement?
A. Friction
B. Gravity
C. Wind
D. Magnetism
A. Friction. The carpet’s surface creates friction against the car’s wheels, slowing it down.
Question 5: In which direction does the force of friction act compared to the direction of motion?
A. In the same direction
B. In the opposite direction
C. Perpendicular to the direction of motion
D. At a 45-degree angle to the direction of motion
B. In the opposite direction. Friction always acts to oppose the motion of an object.
Question 6: Friction occurs when two surfaces have what kind of motion?
A. No motion
B. Relative motion
C. Only upward motion
D. Only downward motion
B. Relative motion. Friction arises when surfaces slide or try to slide against each other.
Question 7: How can we generally measure the force of friction?
A. By measuring the weight of the object
B. By measuring the speed of the object
C. By measuring the force required to initiate or maintain motion
D. By measuring the temperature of the object
C. By measuring the force required to initiate or maintain motion. The force needed to overcome friction is a measure of the friction itself.
Question 8: What happens to the frictional force if you push a heavier object?
A. It decreases
B. It remains the same
C. It increases
D. It disappears completely
C. It increases. A heavier object presses down with more force, leading to increased friction.
Question 9: Which instrument is commonly used to measure force, including friction?
A. Thermometer
B. Ruler
C. Spring balance
D. Stopwatch
C. Spring balance. A spring balance measures the force required to move an object against friction.
Question 10: What principle does a spring balance use to measure force?
A. The extension of a spring is proportional to the force applied.
B. The temperature of a spring changes with the force applied.
C. The color of a spring changes with the force applie
D. D. The weight of a spring changes with the force applied.
A. The extension of a spring is proportional to the force applied. This principle allows the spring balance to accurately measure the force.
Question 11: Which surface would generally create more friction against a moving object?
A. Smooth glass
B. A rough road
C. Polished ice
D. Calm water
B. A rough road. Rough surfaces have more irregularities that create friction.
Question 12: Why does a book slide more easily on a polished tabletop than on a rough carpet?
A. The tabletop is heavier than the carpet
B. The tabletop has less friction than the carpet
C. The tabletop is colder than the carpet
D. The tabletop is larger than the carpet
B. The tabletop has less friction than the carpet. Polished surfaces offer less resistance to motion.
Question 13: Which of the following is an example of increasing friction intentionally?
A. Oiling a door hinge
B. Adding wheels to a suitcase
C. Spreading sand on a slippery road
D. Waxing a car
C. Spreading sand on a slippery road. The sand increases the roughness and thus the friction.
Question 14: How does the smoothness of surfaces affect friction?
A. Smoother surfaces have more friction
B. Smoother surfaces have less friction
C. Smoothness does not affect friction
D. Smoother surfaces only have static friction
B. Smoother surfaces have less friction. Fewer irregularities mean less interlocking and less friction.
Question 15: If we make a surface extremely smooth, what happens to the friction?
A. It becomes extremely large
B. It remains the same
C. It is reduced significantly
D. It becomes zero
C. It is reduced significantly. While complete elimination is impossible, smoothing greatly reduces friction.
Question 16: What causes friction at the microscopic level?
A. The color of the surfaces
B. The temperature of the surfaces
C. The interlocking of surface irregularities
D. The weight of the objects
C. The interlocking of surface irregularities. Even seemingly smooth surfaces have tiny bumps and grooves that catch on each other.
Question 17: Imagine two surfaces rubbing against each other. What would happen to friction if these surfaces have more irregularities?
A. Friction would decrease
B. Friction would increase
C. Friction would stay the same
D. Friction would become zero
B. Friction would increase. More irregularities mean more interlocking and greater resistance to motion.
Question 18: What happens to the force of friction when you press two surfaces together harder?
A. It decreases
B. It stays the same
C. It increases
D. It disappears
C. It increases. Pressing harder increases the contact between irregularities, leading to higher friction.
Question 19: Why is it harder to push a heavy box across the floor than a light one?
A. The heavy box has more gravity
B. The heavy box has more friction
C. The heavy box has more air resistance
D. The heavy box has more magnetism
B. The heavy box has more friction. Its weight presses it harder against the floor, increasing friction.
Question 20: Does friction depend on the types of surfaces in contact?
A. No, friction is the same for all surfaces
B. Yes, rougher surfaces create more friction
C. Yes, smoother surfaces create more friction
D. No, the nature of the surfaces does not matter
B. Yes, rougher surfaces create more friction. Different materials and textures have varying degrees of friction.
Question 21: Why is it harder to walk on ice than on a dry road?
A. Ice is colder than the road
B. Ice is smoother than the road, offering less friction
C. Ice is wetter than the road
D. Ice is harder than the road
B. Ice is smoother than the road, offering less friction. The reduced friction makes it difficult to get a grip and walk safely.
Question 22: What type of friction prevents an object from moving when a force is first applied?
A. Sliding friction
B. Rolling friction
C. Static friction
D. Fluid friction
C. Static friction. Static friction is the initial resistance that needs to be overcome to start an object moving.
Question 23: Imagine trying to push a heavy box. You apply a small force, but it doesn’t move. What kind of friction is acting on the box?
A. Rolling friction
B. Sliding friction
C. Static friction
D. No friction
C. Static friction. The static friction is strong enough to prevent the box from moving initially.
Question 24: Which type of friction is usually the highest?
A. Sliding friction
B. Rolling friction
C. Static friction
D. They are all the same
C. Static friction. It generally takes more force to overcome static friction and start an object moving than to keep it moving.
Question 25: What happens to static friction once an object starts moving?
A. It increases
B. It stays the same
C. It is replaced by sliding friction
D. It disappears
C. It is replaced by sliding friction. Once the object is in motion, sliding friction takes over.
Question 26: What type of friction acts on an object sliding over a surface?
A. Static friction
B. Rolling friction
C. Sliding friction
D. Fluid friction
C. Sliding friction. This friction occurs while the object is in motion, sliding against the surface.
Question 27: Which type of friction is generally less than static friction?
A. Rolling friction
B. Sliding friction
C. They are usually the same
D. Static friction is always less than sliding friction
B. Sliding friction. It’s usually easier to keep an object moving than to start it moving from rest.
Question 28: Why is it slightly easier to push a box once it’s already moving?
A. Because the weight of the box decreases
B. Because sliding friction is less than static friction
C. Because the box gains momentum
D. Because gravity helps
B. Because sliding friction is less than static friction. Once the initial static friction is overcome, less force is needed to maintain the motion.
Question 29: What happens to sliding friction if the surfaces in contact become rougher?
A. It decreases
B. It increases
C. It stays the same
D. It becomes zero
B. It increases. Rougher surfaces create more resistance to sliding.
Question 30: Give an example of sliding friction in action.
A. A ball rolling down a hill
B. A car braking to a stop
C. A boat floating on water
D. A bird flying in the air
B. A car braking to a stop. The brake pads create sliding friction against the wheels, slowing the car down.
Question 31: Why is friction important for walking?
A. It makes us walk faster
B. It prevents our feet from slipping
C. It makes us lighter
D. It helps us fly
B. It prevents our feet from slipping. Friction provides the grip needed for controlled movement.
Question 32: How does friction help a car move?
A. It makes the car lighter
B. It provides grip between the tires and the road
C. It reduces the car’s speed
D. It allows the car to fly
B. It provides grip between the tires and the road. This grip is essential for acceleration and turning.
Question 33: What would happen if there was no friction between a pen and paper?
A. We could write easily
B. The pen would slip and we couldn’t write
C. The pen would become heavier
D. The paper would catch fire
B. The pen would slip and we couldn’t write. Friction is necessary for the pen to leave a mark on the paper.
Question 34: How do brakes on a bicycle work?
A. By reducing the weight of the bicycle
B. By increasing the speed of the bicycle
C. By using friction to slow down the wheels
D. By making the wheels smoother
C. By using friction to slow down the wheels. The brake pads create friction against the wheels, reducing their speed.
Question 35: Why is friction important when lighting a match?
A. It makes the matchstick colder
B. It creates the flame
C. It provides the grip to strike the match
D. It makes the matchstick heavier
C. It provides the grip to strike the match. Friction ignites the match head when it is struck against the rough surface.
Question 36: What is a major disadvantage of friction?
A. It makes objects heavier
B. It produces heat, wasting energy
C. It makes surfaces smoother
D. It increases the speed of moving objects
B. It produces heat, wasting energy. This heat generation can lead to wear and tear in machines.
Question 37: How does friction affect the efficiency of machines?
A. It makes them more efficient
B. It has no effect on their efficiency
C. It makes them less efficient due to energy loss
D. It makes them lighter
C. It makes them less efficient due to energy loss. Overcoming friction requires extra energy, reducing efficiency.
Question 38: Why do machines wear out over time?
A. Due to their age
B. Due to the force of gravity
C. Due to friction causing wear and tear
D. Due to changes in temperature
C. Due to friction causing wear and tear. Constant rubbing leads to damage and wear.
Question 39: How does friction affect the speed of moving objects?
A. It increases their speed
B. It has no effect on their speed
C. It slows them down
D. It makes them lighter
C. It slows them down. Friction acts against motion, reducing speed.
Question 40: Why do we add oil to engines?
A. To increase friction
B. To make the engine heavier
C. To reduce friction and wear
D. To change the engine’s color
C. To reduce friction and wear. Oil acts as a lubricant, minimizing friction between moving parts.
Question 41: Why do we use treads on tires?
A. To make the car look good
B. To increase friction for better grip
C. To reduce the car’s weight
D. To make the tires last longer
B. To increase friction for better grip. The treads provide more contact with the road, improving traction.
Question 42: Why do athletes use special shoes with spikes?
A. To make them run faster
B. To increase friction and prevent slipping
C. To reduce their weight
D. To make them jump higher
B. To increase friction and prevent slipping. The spikes dig into the ground, providing extra grip.
Question 43: Why do gymnasts use chalk on their hands?
A. To make their hands softer
B. To increase friction for a better grip
C. To reduce sweating
D. To make their hands look white
B. To increase friction for a better grip. Chalk absorbs moisture and increases the friction between their hands and the equipment.
Question 44: Why do we use sandpaper to smooth surfaces?
A. To reduce friction
B. To increase friction and remove material
C. To make the surface shiny
D. To change the color of the surface
B. To increase friction and remove material. The rough texture of sandpaper creates enough friction to wear away the surface.
Question 45: What is the purpose of using anti-slip mats in bathrooms?
A. To reduce friction
B. To increase friction and prevent slipping
C. To make the bathroom look good
D. To absorb water
B. To increase friction and prevent slipping. The mats provide a textured surface for better grip.
Question 46: Why do we add oil to a squeaky door hinge?
A. To increase friction
B. To make the hinge stronger
C. To reduce friction and noise
D. To clean the hinge
C. To reduce friction and noise. The oil lubricates the hinge, allowing it to move more smoothly and quietly.
Question 47: How does applying grease to the chain of a bicycle help?
A. It increases friction
B. It makes the chain rust
C. It reduces friction and makes pedaling easier
D. It makes the chain heavier
C. It reduces friction and makes pedaling easier. Grease acts as a lubricant, reducing friction between the moving parts of the chain.
Question 48: Why do mechanics use lubricants in car engines?
A. To increase friction between engine parts
B. To reduce friction and wear, improving efficiency
C. To make the engine run louder
D. To cool down the engine
B. To reduce friction and wear, improving efficiency. Lubricants like oil reduce friction between moving parts, leading to less wear and tear and better fuel economy.
Question 49: What is the purpose of using ball bearings in machines?
A. To increase friction
B. To convert sliding friction into rolling friction, reducing friction overall
C. To make the machine heavier
D. To make the machine look more complex
B. To convert sliding friction into rolling friction, reducing friction overall. Ball bearings allow parts to roll over each other, which has less friction than sliding.
Question 50: Why is it easier to move a heavy box on a wheeled cart than to slide it across the floor?
A. The cart reduces the weight of the box
B. The wheels reduce friction
C. The cart makes the box smoother
D. The cart changes the direction of gravity
B. The wheels reduce friction. Rolling friction is less than sliding friction, making it easier to move the box.
Question 51: What are lubricants?
A. Substances that increase friction
B. Substances that make surfaces rough
C. Substances that reduce friction between surfaces
D. Substances that make objects heavier
C. Substances that reduce friction between surfaces. Lubricants create a smooth layer between surfaces, reducing contact and friction.
Question 52: Which of the following is NOT an example of a lubricant?
A. Oil
B. Grease
C. Graphite
D. Sandpaper
D. Sandpaper. Sandpaper is abrasive and increases friction.
Question 53: How do lubricants reduce friction?
A. By making surfaces rougher
B. By increasing the contact between surfaces
C. By creating a thin layer between surfaces, preventing direct contact
D. By making objects heavier
C. By creating a thin layer between surfaces, preventing direct contact. This separation reduces the interlocking of surface irregularities.
Question 54: Why is it important to use the correct type of lubricant for a specific machine?
A. All lubricants are the same
B. Different machines have different requirements for friction and lubrication
C. The type of lubricant does not matter
D. Using the wrong lubricant will make the machine faster
B. Different machines have different requirements for friction and lubrication. Factors like temperature, pressure, and the types of materials involved influence the choice of lubricant.
Question 55: What could happen if you use too much lubricant in a machine?
A. It will make the machine more efficient
B. It will cause the machine to overheat
C. It will attract dust and dirt, potentially causing damage
D. It will make the machine rust
C. It will attract dust and dirt, potentially causing damage. Excess lubricant can become a problem by trapping contaminants.
Question 56: Why do some machines use air as a lubricant?
A. Air is heavy and provides extra support
B. Air creates a cushion between surfaces, reducing friction without the need for oil or grease
C. Air makes the machine run faster
D. Air cools down the machine
B. Air creates a cushion between surfaces, reducing friction without the need for oil or grease. This is useful in situations where traditional lubricants are not suitable.
Question 57: What is the main purpose of lubricating a bicycle chain?
A. To make the chain shiny
B. To prevent the chain from rusting
C. To reduce friction and make pedaling easier
D. To increase the weight of the chain
C. To reduce friction and make pedaling easier. A well-lubricated chain reduces the effort required for cycling.
Question 58: Why are lubricants important in reducing wear and tear in machines?
A. They make the machine parts softer
B. They reduce the contact between surfaces, preventing damage from friction
C. They make the machine run colder
D. They prevent the machine from getting old
B. They reduce the contact between surfaces, preventing damage from friction. Less friction means less wear and tear, extending the life of the machine.
Question 59: Can lubricants completely eliminate friction?
A. Yes, with enough lubricant, friction becomes zero
B. No, lubricants can only reduce friction, not eliminate it completely
C. Yes, but only in machines that use air as a lubricant
D. No, friction can only be eliminated by making surfaces perfectly smooth
B. No, lubricants can only reduce friction, not eliminate it completely. Some friction will always exist between surfaces, even with lubrication.
Question 60: Why is it important to regularly lubricate moving parts in machines?
A. To change the color of the machine parts
B. To keep the machine clean
C. To maintain low friction and prevent wear and tear
D. To make the machine heavier
C. To maintain low friction and prevent wear and tear. Regular lubrication ensures smooth operation and prolongs the life of the machine.
Question 61: What type of friction occurs when a ball rolls on the ground?
A. Static friction
B. Sliding friction
C. Rolling friction
D. Fluid friction
C. Rolling friction. Rolling friction is the resistance encountered when an object rolls over a surface.
Question 62: Why is rolling friction generally less than sliding friction?
A. Because rolling objects are lighter
B. Because rolling involves less surface area in contact
C. Because rolling objects move faster
D. Because rolling objects have smoother surfaces
B. Because rolling involves less surface area in contact. This reduced contact area leads to less interlocking and friction.
Question 63: What is the advantage of using wheels on a suitcase?
A. It makes the suitcase lighter
B. It reduces friction, making it easier to pull
C. It makes the suitcase more stylish
D. It prevents the suitcase from getting scratched
B. It reduces friction, making it easier to pull. The wheels convert sliding friction to rolling friction, which is easier to overcome.
Question 64: Why do we use rollers to move heavy objects?
A. To increase friction
B. To reduce friction and make it easier to move the object
C. To lift the object off the ground
D. To prevent the object from tipping over
B. To reduce friction and make it easier to move the object. Rollers reduce the contact area and friction between the object and the ground.
Question 65: What would happen if we tried to slide a heavy box instead of rolling it on logs?
A. It would be easier to move
B. It would require the same amount of force
C. It would be much harder to move due to increased friction
D. The box would break
C. It would be much harder to move due to increased friction. Sliding friction is greater than rolling friction.
Question 66: Which type of friction is generally easier to overcome?
A. Sliding friction
B. Rolling friction
C. They are equally difficult
D. It depends on the weight of the object
B. Rolling friction. Rolling friction is generally much less than sliding friction.
Question 67: Why do cars use wheels instead of sliding on the ground?
A. Wheels look better than sleds
B. Wheels reduce friction, improving efficiency and speed
C. Wheels make the car heavier
D. Wheels make the car easier to steer
B. Wheels reduce friction, improving efficiency and speed. By reducing friction, cars can move faster and use less fuel.
Question 68: What is the main reason for replacing sliding with rolling in most machines?
A. To make the machine look more complex
B. To increase the machine’s speed
C. To reduce friction and improve efficiency
D. To make the machine heavier
C. To reduce friction and improve efficiency. Reducing friction leads to less wear and tear, lower energy consumption, and better performance.
Question 69: Why is it easier to ride a bicycle than to drag your feet on the ground?
A. Bicycles are lighter than shoes
B. Bicycles have gears that help us move faster
C. Bicycle wheels reduce friction, making movement easier
D. Bicycles have a more aerodynamic shape
C. Bicycle wheels reduce friction, making movement easier. The rolling friction of the wheels is much less than the sliding friction of your feet on the ground.
Question 70: What would happen if we used sliding instead of rolling in most machines?
A. Machines would be more efficient
B. Machines would last longer
C. Machines would require more energy to operate and wear out faster
D. Machines would be easier to build
C. Machines would require more energy to operate and wear out faster. Increased friction leads to higher energy consumption and increased wear and tear.
Question 71: What are ball bearings?
A. Small balls used in sports
B. Round objects used to increase friction
C. Small, smooth balls used to reduce friction in machines
D. Decorative balls used in jewelry
C. Small, smooth balls used to reduce friction in machines. Ball bearings convert sliding friction to rolling friction, reducing friction overall.
Question 72: How do ball bearings reduce friction?
A. By making surfaces smoother
B. By separating surfaces with small, rolling balls
C. By increasing the contact area between surfaces
D. By making objects lighter
B. By separating surfaces with small, rolling balls. The balls allow parts to roll over each other instead of sliding, reducing friction.
Question 73: Where are ball bearings commonly used?
A. In food processing
B. In bicycles, ceiling fans, and other machines with rotating parts
C. In construction
D. In agriculture
B. In bicycles, ceiling fans, and other machines with rotating parts. Ball bearings help these parts rotate smoothly and with less friction.
Question 74: What is the main advantage of using ball bearings in machines?
A. They make the machine heavier
B. They reduce friction, leading to less wear and tear and improved efficiency
C. They make the machine look more complex
D. They increase the machine’s speed
B. They reduce friction, leading to less wear and tear and improved efficiency. By reducing friction, ball bearings help machines last longer and use less energy.
Question 75: What could happen if ball bearings in a machine are damaged or worn out?
A. The machine will become more efficient
B. The machine will run smoother
C. The machine will become less efficient and may overheat due to increased friction
D. The machine will become lighter
C. The machine will become less efficient and may overheat due to increased friction. Damaged ball bearings can increase friction, leading to problems like overheating and reduced performance.
Question 76: What is fluid friction?
A. Friction that occurs between two solid surfaces
B. Friction that occurs when an object moves through a fluid
C. Friction that occurs when an object is not moving
D. Friction that occurs only in liquids
B. Friction that occurs when an object moves through a fluid. Fluid friction is the resistance experienced by objects moving in liquids or gases.
Question 77: What is a fluid?
A. Only liquids
B. Only gases
C. Any substance that flows, including liquids and gases
D. Any solid substance
C. Any substance that flows, including liquids and gases. Fluids take the shape of their container and can exert friction on objects moving through them.
Question 78: Why do objects moving in fluids experience friction?
A. Because fluids are sticky
B. Because fluids have weight
C. Because fluids exert a force against the motion of the object
D. Because fluids are always cold
C. Because fluids exert a force against the motion of the object. This opposing force is the fluid friction or drag.
Question 79: What is another name for fluid friction?
A. Static friction
B. Rolling friction
C. Drag
D. Lubrication
C. Drag. Drag is the common term for the frictional force experienced by objects moving through fluids.
Question 80: Why do airplanes have a streamlined shape?
A. To increase drag
B. To reduce drag and improve efficiency
C. To make them look good
D. To make them fly higher
B. To reduce drag and improve efficiency. The streamlined shape minimizes the resistance from the air, allowing the plane to fly more efficiently.
Question 81: How does drag affect the speed of a swimmer?
A. It makes them swim faster
B. It has no effect on their speed
C. It slows them down
D. It makes them float
C. It slows them down. The water creates resistance (drag) against the swimmer’s body, reducing their speed.
Question 82: Why do birds have a streamlined body shape?
A. To increase drag
B. To reduce drag and make flying easier
C. To attract mates
D. To protect them from predators
B. To reduce drag and make flying easier. The streamlined shape helps birds minimize air resistance during flight.
Question 83: What factors affect the amount of drag an object experiences?
A. Only the speed of the object
B. Only the shape of the object
C. Only the type of fluid
D. The speed, shape, and the nature of the fluid
D. The speed, shape, and the nature of the fluid. All these factors influence the amount of drag.
Question 84: How does the speed of an object affect drag?
A. Higher speed creates less drag
B. Speed has no effect on drag
C. Higher speed creates more drag
D. Drag is always constant
C. Higher speed creates more drag. As the object moves faster, it encounters more resistance from the fluid.
Question 85: Why does a parachute slow down a skydiver?
A. It makes the skydiver heavier
B. It increases drag, opposing the force of gravity
C. It makes the skydiver more streamlined
D. It creates a vacuum around the skydiver
B. It increases drag, opposing the force of gravity. The parachute’s large surface area increases air resistance, slowing the descent.
Question 86: How does the shape of a boat’s hull affect its speed?
A. A wider hull is faster
B. A more streamlined hull reduces drag and increases speed
C. The shape of the hull has no effect on speed
D. A rough hull is faster
B. A more streamlined hull reduces drag and increases speed. By minimizing water resistance, the boat can move faster through the water.
Question 87: Why are cars designed with smooth, curved shapes?
A. To increase drag
B. To reduce drag and improve fuel efficiency
C. To make them look modern
D. To make them safer
B. To reduce drag and improve fuel efficiency. The smooth shape minimizes air resistance, allowing the car to use less fuel.
Question 88: What is the benefit of designing airplanes with a streamlined shape?
A. It makes them easier to build
B. It allows them to carry more passengers
C. It reduces drag, allowing them to fly faster and use less fuel
D. It makes them fly lower
C. It reduces drag, allowing them to fly faster and use less fuel. The streamlined shape minimizes air resistance, improving efficiency and speed.
Question 89: Why do fish have a streamlined body shape?
A. To make them look attractive
B. To reduce drag and swim more efficiently
C. To help them breathe underwater
D. To protect them from predators
B. To reduce drag and swim more efficiently. The streamlined shape minimizes water resistance, allowing fish to swim faster and use less energy.
Question 90: What would happen if cars were designed with sharp, angular shapes?
A. They would be more fuel-efficient
B. They would experience more drag, reducing speed and fuel efficiency
C. They would be easier to drive
D. They would be safer
B. They would experience more drag, reducing speed and fuel efficiency. The increased air resistance would make the car less efficient and slower.
Question 91: What is the force that opposes motion between two surfaces in contact?
A. Gravity
B. Friction
C. Magnetism
D. Inertia
B. Friction. This is the fundamental definition of friction.
Question 92: What are substances used to reduce friction between surfaces called?
A. Fuels
B. Lubricants
C. Solvents
D. Adhesives
B. Lubricants. Lubricants like oil and grease reduce friction.
Question 93: What is the friction that occurs when an object moves through a fluid called?
A. Static friction
B. Rolling friction
C. Fluid friction
D. Sliding friction
C. Fluid friction. This is the resistance experienced by objects moving in liquids or gases.
Question 94: What is the force that opposes the motion of an object through a fluid?
A. Thrust
B. Lift
C. Drag
D. Weight
C. Drag. Drag is another term for fluid friction.
Question 95: What is the phenomenon of surface irregularities catching on each other called?
A. Adhesion
B. Cohesion
C. Interlocking
D. Repulsion
C. Interlocking. This interlocking contributes to friction.
Question 96: What is a type of bearing that uses balls to maintain the separation between the bearing races?
A. Ball bearing
B. Roller bearing
C. Sleeve bearing
D. Journal bearing
A. Ball bearing. Ball bearings reduce friction by converting sliding to rolling.
Question 97: What is the friction that occurs when an object rolls over a surface called?
A. Static friction
B. Sliding friction
C. Rolling friction
D. Fluid friction
C. Rolling friction. This type of friction is generally less than sliding friction.
Question 98: What is the friction that occurs when two surfaces slide over each other called?
A. Static friction
B. Rolling friction
C. Sliding friction
D. Fluid friction
C. Sliding friction. This occurs when two surfaces are in motion relative to each other.
Question 99: What is the friction that prevents an object from moving when a force is applied called?
A. Static friction
B. Rolling friction
C. Sliding friction
D. Fluid friction
A. Static friction. This is the initial friction that needs to be overcome to start an object moving.
Question 100: Which of the following is NOT a type of friction?
A. Static friction
B. Magnetic friction
C. Rolling friction
D. Fluid friction
B. Magnetic friction. This is not a real type of friction.
