Question

All questions are compulsory)
Q1) a) Name the objects between which the friction is caused in the given cases
b) When a child is paddling a bicycle
ii) Writing on the black board with a piece of chalk
b) when you apply the brakes, the bicycle stops and the rim or the wheel bocomes hot. Give reason
c) Two forces of 20 kgfacts on a body in the same direction Calculate the net force acting on the body (i) in
kgf (ii) newtons
d) Naune the different types of friction and write them in them is the increasing order. (2)
c) What are the changes we notice when we stretch a rubber bund. (2)​

Answer 1

Answer:

a) when a child is paddling the bike the friction caused it between the tyres of the bike and the road.

b)when you are writing on the blackboard with a piece of chalk, thee friction is caused between the chalk and surface of the board.

c)when you apply breaks, the rim of the wheel becomes hot as friction is caused between the brake pads and the wheels to make the vehicle stop.

c)the net force acting on the body=

20kg+20kg (as the force is acting in the same direction)

=40kg

d)

Types Of Friction

Following are the friction types which depend on the types of motion:

Static Friction

Sliding Friction

Rolling Friction

Fluid Friction

c)when we strech a rubber band we notice change in shape which is the effect of force.