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 $J$)

The work done by a force on a body will be positive if the:

What is the work done by the earth in moving around the sun?

$A$ mass of $10 \, kg$ is dropped from a height of $50 \, cm$. Find its:
$(a)$ Potential energy just before dropping.
$(b)$ Kinetic energy just on touching the ground.
$(c)$ Velocity with which it hits the ground. (Given: $g = 10 \, m s^{-2}$)

Which would have a greater effect on the kinetic energy of an object: doubling the mass,or doubling the velocity?

Define watt. Express kilowatt in terms of joule per second. $A$ $150 \, kg$ car engine develops $500 \, W$ for each $kg$. What force does it exert in moving the car at a speed of $20 \, m \, s^{-1}$ (in $N$)?