When balanced forces act on a body,the body is

$(a)$ Define force and state three possible effects of force on an object.
$(b)$ $A$ motorcycle is moving with a velocity of $90 \, km \, h^{-1}$ and it takes $5 \, s$ to stop after the brakes are applied. Calculate the force exerted by the brakes on the motorcycle if its mass along with the rider is $200 \, kg$.

$(a)$ State Newton's second law of motion. Express it mathematically and find the $SI$ unit of force from it.
$(b)$ In the diagram given below, if the card is flicked away with a jerk, what will you observe? Explain the reason for this observation.

While riding a bicycle,if we stop pedalling,why does the bicycle begin to slow down?

What force would be needed to produce an acceleration of $4 \, m s^{-2}$ on a ball of mass $6 \, kg$?

What are the changes possible on an object at rest if we apply on it:
$(a)$ a balanced force?
$(b)$ an unbalanced force?