Energy stored in a spring

  • Thread starter Jahnavi
  • Start date
  • #1
848
102

Homework Statement


block.jpg


Homework Equations




The Attempt at a Solution



If I work in the lab frame I get the correct answer 4J .

But I do not understand why I do not get the correct answer if I work in the moving frame of block B .

After collision with block A , block B starts moving with 2m/s towards right .

Now in the frame of B , initial velocity of C is 2m/s towards left . Total initial mechanical energy = (1/2)(6)(22) = 12J .

In this frame spring will have maximum compression when C is at rest .That means maximum potential energy should be 12 J .

What is the mistake ?

The same problem arises if I work in the frame of block C .

So why is it that energy conservation is not holding true in the moving frames ?
 

Attachments

  • block.jpg
    block.jpg
    19.3 KB · Views: 459
Last edited:

Answers and Replies

  • #2
haruspex
Science Advisor
Homework Helper
Insights Author
Gold Member
2020 Award
36,736
7,082
the moving frame of block B .
That will not be an inertial frame. KE appears different in different frames, even inertial ones, so in a non-inertial frame it will not be conserved.
 

Related Threads on Energy stored in a spring

  • Last Post
Replies
11
Views
22K
  • Last Post
Replies
4
Views
1K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
1
Views
9K
  • Last Post
Replies
2
Views
573
Replies
7
Views
3K
  • Last Post
Replies
2
Views
2K
Replies
7
Views
794
  • Last Post
Replies
4
Views
2K
Replies
1
Views
1K
Top