What is horsepower?

Compare the power at which each of the following is moving upwards against the force of gravity? (given $g = 10 \, m \, s^{-2}$)
$(i)$ $A$ butterfly of mass $1.0 \, g$ that flies upward at a rate of $0.5 \, m \, s^{-1}$.
$(ii)$ $A$ $250 \, g$ squirrel climbing up on a tree at a rate of $0.5 \, m \, s^{-1}$.

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 $N$)?

How is the power related to the speed at which a body can be lifted? How many kilograms will a man working at the power of $100\, W$ be able to lift at a constant speed of $1\, m\, s^{-1}$ vertically (in $, kg$)? $(g = 10\, m\, s^{-2})$

Name at least three commonly used units of energy.

Name the practical unit of power in engineering.