Question

Assertion (A): A book lying on a table stays at rest even though the Earth pulls it downwards. Reason (R): The upward push of the table on the book balances the downward pull of gravity, so the net force is zero.

Assertion (A): Friction opposes the relative motion between two surfaces in contact. Reason (R): Friction is a non-contact force.

What is muscular force? Give two examples from daily life and state whether it is a contact or non-contact force.

At a school science fair, Kabir shows two experiments. In the first, he brings a bar magnet near a few steel pins lying on a table; the pins jump up and stick to the magnet before touching it. In the second, he rubs an inflated balloon on his woollen sweater and holds it near a thin stream of water from a tap; the stream bends towards the balloon.