Physics Problems (2) : Work & Power

Question

• A weightlifter lifts a 50 kg barbell 2.5 meters into the air. How much work does she do on a barbell? How much potential energy does the barbell have at the top?
• If she lifts the barbell in 2 seconds, how much power does she have?

 

Show all work for both.

Answer 1

W = Fd = (mg)h = (50 kg)(9.8 m/s^2)(2.5 m) = 1225 J

 

PE = 1225 J

 

P = W/t = (1225 J) / (2 s) = 612.5 watts