Question

Please answer these questions .

A. Fill in the blanks.
1. The force acting between the two surfaces,whenever an object moves or tends to
move over the surface of another object is called the ——— —- ———-.
2. ———— friction is a self- adjusting force.
3. The more is the ———— of the two surfaces in contact, more is the force of friction.
4. Friction——— up our palms in winter.
5. We ——- the ground under our feet backwards, when we walk.
B. State True or False.
1. Sliding friction is a little more than static friction between two surfaces. ———.
2. It’s much easier to roll than to slide a body over a given surface. ———.
3. Static friction 4. Friction leads to production of heat. ———.
5. We are unable to write on the blackboard because of friction. ———.
C. Match the following.
1. Streamlined body. Opposes motion
2. Ball bearings Friction between ground & feet
3. Static friction Fish
4. Walking Snow on roads
5. Sand. Excessive heat
6. Machine parts. Grooves for grip
7. Tyres. Shafts of motors
D. Give reasons for the following.
1. Air resistance increases with increase in speed of the moving object.
2. We sprinkle talcum powder on the board when we play carrom.
3. It is slippery and difficult to walk on a floor with new tiles.
4. Birds and aeroplanes have streamlined bodies.
5. Roller skates have ball bearings in the wheels.
E. Answer the following.
1. Understanding rolling friction had lead to a revolution in the transport industry.
Comment.
2. Sports cars come with very special shapes. Explain.
3. Explain ,what are the causes of friction.
4. What are the factors that affect friction? Explain with an example.
5. Why are the soles of our shoes treaded?

Answer 1

Answer:

A

1. Fictional force

2. Static

3. interlocking

4. heats

5. push

Answer 2

Answer:

i)frictional force

ii)limiting

iii)atoms

iv)is produced (when we rub our hands in winter)

v)push

B

i)T

ii)T

iii)T

iv)F