Group 1
1) A student rubs two surfaces together. Which statement is always correct?
A. Friction increases the speed of the surfaces.
B. Friction acts only if the surfaces are rough.
C. Friction opposes the relative motion between the surfaces.
D. Friction acts only after the surfaces start moving.
C. Friction opposes the relative motion between the surfaces.
1) Which property of a surface mainly determines the amount of friction produced?
A. Colour
B. Nature (roughness or smoothness)
C. Shape
D. Temperature
B. Nature (roughness or smoothness)
1) Which of the following is NOT a method to reduce friction?
A. Polishing surfaces
B. Applying lubricants
C. Making surfaces rough
D. Using smooth surfaces
C. Making surfaces rough
1) Why are tyre grooves provided?
A. To reduce the weight of the tyre
B. To increase friction with the road
C. To make tyres look attractive
D. To reduce air pressure
B. To increase friction with the road
2) A rough surface is polished. Which change is most likely to occur?
A. Friction increases.
B. Friction decreases.
C. Friction remains exactly the same.
D. Friction disappears completely.
B. Friction decreases.
2) Which of the following correctly explains why friction produces heat?
A. Heat comes from the air.
B. Friction converts part of the motion energy into heat.
C. Friction creates energy.
D. Heat is produced only on rough surfaces.
B. Friction converts part of the motion energy into heat.
2) Which pair is correctly matched?
A. Lubricants — Increase friction
B. Rough surfaces — Reduce friction
C. Tyre grooves — Increase friction
D. Polishing — Increase friction
C. Tyre grooves — Increase friction
2) Which statement is incorrect?
A. Friction causes wear and tear.
B. Friction helps us write.
C. Friction can produce heat.
D. Friction always makes machines work better.
D. Friction always makes machines work better.
3) Which statement best explains why friction is called a necessary evil?
A. It is always harmful.
B. It is always useful.
C. It is essential for many activities but also causes energy loss and wear.
D. It is found only in machines.
C. It is essential for many activities but also causes energy loss and wear.
3) Which of the following would NOT work properly if friction were absent?
A. Writing with a pencil
B. Holding a glass firmly
C. Walking
D. All of the above
D. All of the above
3) A student says, "The smoother the surface, the greater the friction."
Which option correctly evaluates this statement?
A. Correct, because smooth surfaces stop motion quickly.
B. Incorrect, because smoother surfaces generally produce less friction.
C. InCorrect only for wooden surfaces.
D. Correct only for metal surfaces.
B. Incorrect, because smoother surfaces generally produce less friction.
3) Which statement is always true?
A. Increasing friction is always beneficial.
B. Reducing friction is always beneficial.
C. Whether friction should be increased or reduced depends on its use.
D. Friction should always be eliminated.
C. Whether friction should be increased or reduced depends on its use.