Question

q.6 where does friction help us?
a. wearing out parts of a machine.
b. stop a car.
c. writing with a pencil.
d. both b and c.

Explanation:

Friction helps in writing with a pencil as it allows the graphite to stick to the paper. It also helps in stopping a car as the friction between the brakes and the wheels slows down the vehicle. Wearing out parts of a machine is a negative effect of friction, not a helpful one.

Answer:

d. Both B and C