Find average power by elevator motor?

A 646 kg elevator starts from rest. It moves up ward from 3.98 s with a constant acceleration until it reaches its cruising speed of 2.06 m/s. The acceleration of gravity is 9.8 m/s^2. Find the average power delivered by the elevator motor during the period of this acceleration.


I first used vf=vi +at to find a and i got a=0.52 m/s^2. Then I tried to find the force by plugging in F=ma to get 334.36 N. Then I tried to find W (W=Fx). How do i find x though. Is that d=v/t. I got 173.06 Nm for work. then for average p= W/t which i got 43.48. Is this correct??

Find average power by elevator motor?
Hmm...





You need to find the resultant force, that is the F from F=ma (334.36) minus the weight (W = mg, where g = 9.8)





To find x, use v^2 = u^2 + 2ax.


v = final = 2.06, u = 0 because from rest, a you have calculated.





Hence x = (v^2 - u^2)/2a.





Then use that with the resultant force multiplied by the distance (x) to find the average power of the motor.
Reply:Vf = Vo + sqrt(2*a*x) solve for x





Xf = Xo +Vo*t + 0.5*a*t^2 solve for x

teeth