Answer:
W = 1493.9 J = 1.49 KJ
Explanation:
The work done by the elevator on the object will be equal to the gain in is potential energy:
W = ΔP.E
W = mgΔh
where,
W = Work = ?
m = mass of object = 7.4 kg
g = 9.8 m/s²
Δh = gain in height = 20.6 m
Therefore,
W = (7.4 kg)(9.8 m/s²)(20.6 m)
<u>W = 1493.9 J = 1.49 KJ</u>
v=28m/s
Conservation of Energy
Ei=Ef
mgh= 1/2mv^2
9.8*40*2= v^2
784= v^2
v= 28m/s
A. 280