$A$ ball is thrown vertically upwards. What is its momentum at the highest point?

Suppose a ball of mass $m$ is thrown vertically upward with an initial speed $v$. Its speed decreases continuously until it becomes zero. Thereafter,the ball begins to fall downward and attains the speed $v$ again before striking the ground. It implies that the magnitude of the initial and final momentum of the ball are the same. Yet,it is not an example of the conservation of momentum. Explain why?

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

$A$ sledge of mass $80 \, kg$ moves over the frozen surface of a lake with a velocity of $30 \, m s^{-1}$ and comes to rest in $5 \, s$. Find its negative acceleration and the frictional force between the lake and the sledge.

Which of the following statements is not correct for an object moving along a straight path in an accelerated motion?

Explain the following:
$(i)$ Why does a boatman push the river bank backward with a long bamboo pole when launching his boat into the water?
$(ii)$ Why does a boat tend to leave the shore when passengers are alighting from it? How does the boatman overcome this difficulty?
$(iii)$ Why does a gun recoil when fired?
$(iv)$ How do rockets operate in space?