Answer to Question #100379 in Field Theory for Derickson

Question

The power required to lift a certain body through a distance of 30m in 6 seconds is 200 watts. Calculate workdone and mass of the body.

Answer 1

$$\rm work\: done=power\times time$$ $$W=Pt=200\:\rm W\times 6 \:s=1200\: J$$

Also we have

$$W=mgh$$

So, the mass of the body

$$m=\frac{W}{gh}=\frac{1200\:\rm J}{10\rm N/kg\times 30\: m}=4\: \rm kg$$