Power = Work / time
The work given here is 83J and the time it took to do 83J of work was 3s
So..
Power = 83J / 3s
Power = 27.67 W or 27.7 W
No they do not they just need to be in each other's magnetic field
Answer:
208.33 W
141.26626 seconds
Explanation:
E = Energy = 
t = Time taken = 8 h
m = Mass = 2000 kg
g = Acceleration due to gravity = 9.81 m/s²
h = Height of platform = 1.5 m
Power is obtained when we divide energy by time

The average useful power output of the person is 208.33 W
The energy in the next part would be the potential energy
The time taken would be

The time taken to lift the load is 141.26626 seconds