Potential Energy

Question

1. How much work would a 60.0 kg person do in climbing from the surface of the Earth to the top of a mountain 2.00 km high?
a) Use EP = mgh to find your solution. Show all work. (ans. 1.18×106 J)


(I'm getting 1.15 x 10^4) 




b) Use EP = -GMm/r (both answers should be close)

Answer 1

1. PE = mgh

m = 60 kg, g = 9.8 m/s², h = 2000 m.

 

PE = (60 kg)(9.8 m/s²)(2000 m) = 1.18 X 10⁶ J

 

 

Answer 2

a)

 

PE = (2 kg)(9.81 m/s²)(2 x 10³ m)

 

The issue was the you did not convert your height unit from km to m.

 

 

b)

 

Let M and m be the mass of the earth and the mass of the person.

 

Use the value of G, which is Earth's gravitational attraction constant between Earth and the object.  This value can be obtained from your reference table or appendix.

 

Use r as the distance between the person and the Earth.  It should be the same as the height between the Earth's surface and the top of the mountain.