How much momentum will a dumbbell of mass $10 \, kg$ transfer to the floor,if it falls from a height of $0.8 \, m$? Take acceleration due to gravity as $10 \, m s^{-2}$.

In the following cases,identify the direction of the net force acting on the objects:
$(a)$ $A$ car drives around a circular race track at a constant speed.
$(b)$ Earth moving around the sun.
$(c)$ $A$ ball,rolling across a grassy field,slowly comes to a stop.

Identify the type of inertia experienced by the brain,when
$(a)$ the head is hit suddenly with a stick.
$(b)$ a car is suddenly made to stop using brakes.
$(c)$ a boxer punches another boxer in the face.

The velocity versus time graph of a ball of mass $50 \, g$ rolling on a concrete floor is shown in the figure. Calculate the acceleration and the frictional force exerted by the floor on the ball.

$(a)$ If the mass of a body is doubled, what happens to its acceleration when acted upon by the same force? Justify your answer.
$(b)$ It is easier to stop a tennis ball than a cricket ball moving with the same speed. Why?
$(c)$ A girl of mass $40 \, kg$ jumps with a horizontal velocity of $5 \, m s^{-1}$ onto a stationary cart with frictionless wheels. The mass of the cart is $10 \, kg$. Find her velocity as the cart starts moving. Assume that there is no external unbalanced force working in the horizontal direction.

State whether the following statement is true or false:
Force may or may not produce any motion in a body.