Question

At a certain time interval, a lift of 400 kg moving varies its speed 4 m / s to 6 m / s. Determine the value of work in Joules, the force on the lift range.

Answer 1

work done is change in KE + change in PE
change in KE is 1/2 m (v^2 - u^2)
change in PE needs time interval or distance traveled :  m g height gained