What is the work needed to lift 15kg of water from well 12m deep. Assume the water has a constant upward acceleratin of 0.7m/s^2?

Answer 1

F = m*a = 15 * 0.7 = 10.5 N.

Work = F*d = 10.5 * 12 = 126 Joules.

Answer 2

The first response is wrong because 10.5 has to be multiplied by the mass to get the force (tension) needed to lift 15kg from that distance. F-mg=ma=>F=m(g+a)=>F=15(9.8+.7)=>F=15(10.5)=157.5N