$A$ boy pushes the wall in the class for five minutes but the wall does not move. Another boy pushes the chair from the front to the back side of the class. In which case,more work is done?

$A$ horse of mass $210\, kg$ and a dog of mass $25\, kg$ are running at the same speed. Which of the two possesses more kinetic energy? How?

An object of mass $40 \text{ kg}$ is pulled up to a height of $0.5 \text{ m}$. Calculate the work done. (Given $g = 9.8 \text{ m s}^{-2}$) (in $J$)

Given below are a few situations. Study them and state in which of the given cases work is said to be done. Give a reason for your answer:
$(i)$ $A$ person pushing hard a huge rock,but the rock does not move.
$(ii)$ $A$ bullock pulling a cart up to $1 \, km$ on the road.
$(iii)$ $A$ girl pulling a trolley for about $2 \, m$ distance.
$(iv)$ $A$ person standing with a heavy bag on his head.

$A$ force of $10\, N$ moves a body with a constant speed of $2\, m s^{-1}$. Calculate the power of the body.

Is it possible that a body be in accelerated motion under a force acting on the body,yet no work is being done by the force? Explain your answer giving a suitable example.