N2007P1Q9 Pure Physics – Energy needed to pump water up a building

Answer: Option B

Since water will naturally reach 40m high from the bottom of the apartment, you only need to pump the water up by a further 10 m.

Energy needed = GPE = mgh

= 1 x 10 x 10

= 100 J

View this video to understand that when both ends of the tube are exposed to atmospheric pressure, the water levels on each end will be level.