2 weights on a pully

  • Thread starter jfleury45
  • Start date
  • #1
2
0
1. A 3kg weight is attached to a 2kg weight by a rope. This rope is placed over a pully so the weights are hanging. The 2kg weight starts 4 meters lower than the 3kg weight. If the system starts at rest what is the speed of the objects when they are at the same height.



2. Fnet = ma
v^2=2*a*(x2-x1)




3. I took the net force to be the normal force of the 3kg weight minus the normal force of the 2 kg weight. Fnet=9.81N I then divided by 3kg to get a=3.27 m/s^2 I then plugged knowns into v^2=2*a*(x2-x1) v^2=2*3.27*2 and got v=3.617 This answer does not work. What am i doing wrong?
 

Answers and Replies

  • #2
340
0
The normal force usually refers to a force provided by contact between the system and the environment. Try drawing a free body diagram for both objects, then write down newtons second law for both objects. Think about the acceleration of each object, then solve for the acceleration of either. Plug into the kinematic equations.
 

Related Threads on 2 weights on a pully

  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
8
Views
9K
Replies
1
Views
4K
  • Last Post
Replies
2
Views
2K
  • Last Post
Replies
2
Views
2K
Replies
3
Views
5K
Replies
27
Views
8K
  • Last Post
Replies
4
Views
543
  • Last Post
Replies
4
Views
8K
  • Last Post
Replies
11
Views
2K
Top