Question

What is the maximum velocity at which a 60-watt motor can lift an 8.5-kg mass upward?

Answer 1

Pick choice-A .

Weight of a mass = (mass) x (gravity)

Earth gravity = (9.8 m/s )

Weight of a mass = (9.8 x mass) Newtons

Work = (force) x (distance)

Power = (work done) / (time to do the work)

Weight of this mass = (8.5 kg) x ( 9.8 m/s ) = 83.3 Newtons

Work to lift it 1 meter = (83.3 N) x (1 m) = 83.3 Joules

Power to lift it 1 meter/sec = 83.3 Joule/sec = 83.3 watt

Power to lift it ' v ' meters/sec = 83.3v watts

In this problem ...

83.3 v watts = 60 watts

v =  60/83.3 m/s

v =  0.72 m/s