• Support PF! Buy your school textbooks, materials and every day products Here!

A Tension problem with no known angle given

  • Thread starter jenador
  • Start date
  • #1
13
0
here's the question:

Part a of the drawing shows a bucket of water suspended from the pulley of a well; the tension in the rope is 81.5 N. Part b shows the same bucket of water being pulled up from the well at a constant velocity. What is the tension in the rope in part b?

picture:
http://www.webassign.net/CJ/p4-46.gif

equations: F=ma; maybe sin, cos, etc...?

i don't even know where to begin with this since the second situation has no angle given to help solve for the problem. i know that the bucket at rest and the bucket at constant velocity have a=0. i also figured that in situtation 1, since only tension and weight are acting on the bucket in the y direction, the weight equals -81.5. but i do not know where to go from there. any help is appreciated. thanks!
 

Answers and Replies

  • #2
dx
Homework Helper
Gold Member
2,011
18
The angle is not relevant.

In part A of the figure, the rope is attached to the bucket at both ends, so the force on the bucket in terms of the tension in the rope is what? What does that tell you about the weight of the bucket?
 
  • #3
13
0
Oh! Therefore there are two strings that both have 81.5 N of tensions. I assumed 81.5 was the whole amount of tension in both strings. thank you SO much for clearing that up.
 
  • #4
dx
Homework Helper
Gold Member
2,011
18
No, there's only one rope with tension 81.5 N. But this one rope is attached to the bucket at two points. The rope exerts a tension force at both these points. Both these forces point vertically upwards because the string is vertical there, so there is a total force of 2T pointing vertically upwards on the bucket due to the rope.
 

Related Threads for: A Tension problem with no known angle given

Replies
7
Views
1K
Replies
1
Views
2K
Replies
2
Views
2K
  • Last Post
Replies
7
Views
2K
  • Last Post
Replies
4
Views
2K
Replies
7
Views
2K
Replies
3
Views
10K
Top