Friction

Friction Worksheet-10

36. Why does a car stop when brakes are applied?

37. Give three factors on which the frictional force in fluids depends.

38. How has nature shaped the body of fishes to minimize air resistance?

39. A labourer has to push a heavy trunk. What should be done to reduce his effort in pushing it and  why?

40. (a) How do trees help reduce friction?

(b) Why do meteors burn on entering the atmosphere?

Friction Worksheet-11

1. Friction always works in opposite direction of motion of the surface.

2. Irregularities between two surfaces interlock to produce friction.

3. Friction increases with increase in the smoothness of the surface.

4. Soapy floor is slippery due to increased friction.

5. Friction is a necessary evil.

Answer:

1. True

2. True