Give an example of a force that merely changes the direction of motion of a body.

Which of the following has the largest inertia?

$(a)$ Define inertia. You are provided with three bodies made of wood,rubber,and iron of the same shape and size. Which one of them will have greater inertia? Explain it.
$(b)$ When a striker hits the bottom of the pile of coins placed at the centre of a carom board,only the lowest coin is removed. Give reason for it.

$A$ block is supported by a cord $A$ from a rigid support,and another cord $B$ is attached to the bottom of the block. If you give a sudden jerk to $B$,it will break. But if you pull on $B$ steadily,$A$ will break. Why?

Two friends on roller-skates are standing $5\, m$ apart facing each other. One of them throws a ball of $2\, kg$ towards the other,who catches it. How will this activity affect the position of the two? Explain your answer.

$(a)$ Name the force that keeps the object moving in a circular path with constant acceleration.
$(b)$ What would happen if this force is absent?