A machine which is 75 percent efficient, uses 12 joules of energy in lifting up a $1\ kg$ mass through a certain distance. The mass is then allowed to fall through that distance. The velocity at the end of its fall is (in $ms^{- 1}$)

Question

Dr. Abubacker · Accepted Answer

(c) Potential energy of a body $= 75\%$ of $12\ J$
$mgh = 9\ J \Rightarrow h = \frac{9}{1 	imes 10} = 0.9\ m$
Now when this mass allow to fall then it acquire velocity
$v = \sqrt{2gh} = \sqrt{2 	imes 10 	imes 0.9} = \sqrt{18}\ m/s$

Q. A machine which is 75 percent efficient, uses 12 joules of energy in lifting up a $1\ kg$ mass through a certain distance. The mass is then allowed to fall through that distance. The velocity at the end of its fall is (in $ms^{- 1}$)

Explanation

Reviewed by Dr. Abubacker

Want more practice?