Potential Energy Clarification

  • Thread starter MyNewPony
  • Start date
  • #1
31
0
You lift a ball at constant velocity from a height hi to a greater height hf . Considering the ball and the earth together as the system, which of the following statements is true?

1. The potential energy of the system increases.
2. The kinetic energy of the system decreases.
3. The earth does negative work on the system.
4. You do negative work on the system.
5. The source energy of the ball increases.
6. Two of the above.
7. None of the above.

Am I right in thinking that neither 1 nor 2 are correct because the question takes into account BOTH the earth and the ball? They would only be correct if the system was merely the ball, right?
 

Answers and Replies

  • #2
79
1
I believe you are right there.
 
  • #3
Doc Al
Mentor
45,204
1,540
Am I right in thinking that neither 1 nor 2 are correct because the question takes into account BOTH the earth and the ball? They would only be correct if the system was merely the ball, right?
No, gravitational potential energy is a joint property of earth and ball (since gravity is an interaction between them). So #1 is correct.
 

Related Threads on Potential Energy Clarification

Replies
2
Views
283
E
  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
4
Views
628
Replies
1
Views
1K
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
2
Views
5K
Replies
1
Views
1K
Replies
2
Views
3K
  • Last Post
Replies
9
Views
2K
  • Last Post
Replies
7
Views
2K
Top