A mover hoists a 200 kg piano from the ground to a height of 10 m using a single pulley. What was the change in the pianos energy? a. 20j b. 200j c. 2000j d. 20000
P.E= Mass x gravity x height (standard gravity = 10m/s approaximately)
= 200x10x10= 20000j (D)
Answer: d. 20000 J
Explanation:
Potential energy is the energy possessed by an object by virtue of its position.
\(P.E=m\times g\times h\)
m= mass of object = 200 kg
g = acceleration due to gravity = \(10ms^{-2}\)
h = height of an object
1. when h= 10 m
\(P.E=200\times 10ms^{-2}\times 10m=20000Joules\)
2. when h= 0 m
\(P.E=200\times 10ms^{-2}\times 0m=0Joules\)
Thus change in energy=(20000-0)Joules=20000Joules.