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

Compare the power at which each of the following is moving upwards against the force of gravity? (given  $g=10 \mathrm{m} {\mathrm{s}}^{-2}$)

$1.$ A butterfly of mass $1.0 \mathrm{g}$ that flies upward at a rate of $0.5 \mathrm{m} {\mathrm{s}}^{-1 }$.

$2.$ A $250 \mathrm{g}$ squirrel climbing up on a tree at a rate of $0.5 \mathrm{m} {\mathrm{s}}^{-1}$.

Compare the power at which each of the following is moving upwards against the force of gravity? (given  $g=10 \mathrm{m} {\mathrm{s}}^{-2}$)

A $250 \mathrm{g}$ squirrel climbing up on a tree at a rate of $0.5 \mathrm{m} {\mathrm{s}}^{-1}.$