Physics Problems (2) : Work & Power

Question

• How much potential energy does 8 million kg of water have as it drops 50 m over Niagara Falls?
• If a 8 million kg of water flows over Niagara Falls each second, calculate the power available at the bottom of the falls at any one second.

 

Show all work for both.

Answer 1

U = potential energy

 

U = mgh = (8 x 10^6 kg)(9.8 m/s^2)(50 m) = 3.92 x 10^9 J

 

P = available power

 

P = ΔU / Δt = [mgh - mg(0)] / Δt = (3.92 x 10^9 J) / (1 s) = 3.92 x 10^9 watts