Work done by variable force

  • Thread starter kallied
  • Start date
  • #1
2
0

Homework Statement


if a 10-N force is used to compress a spring with a spring constant of 4.0x10^2N/m, what is the resulting spring compression?


Homework Equations





The Attempt at a Solution

 

Answers and Replies

  • #2
168
0
The spring constant tells you something about how great a force is needed to compress the spring 1 m so see if the units give you a hint. It is just a ratio.
I think the problem is about finding the dx (The displacement). Alternativly use newtons 1. law to see where it stands still, and the force seems constant to me:
Fhook - Fpress = 0 => kx - Fpress = 0 <=> x = Fpress/k
Do you get the idea?
 
  • #3
2
0
no not really :(
 
  • #4
172
2
What the spring constant says is: for each meter the spring is compressed, the spring will push back with 400 Newtons more force. The spring in your problem will push back with 400x Newtons of force, where x is the distance you compress it in meters. To get your answer, you must find the compression (x) where this spring exerts 10 Newtons of force.
 
  • #5
168
0
Try imangining you compressing a spring. If you pressed with 10 N, then the spring would try to oppose it(You can feel it trying). If you pressed it until it was half as wide as initially, and stood still there, then the acceleration of the spring equals zero(a=0). Then newtons first law of motion states:
[itex] \sum F = 0[/itex]
The two forces are in opposite directions(you pressing and the spring pressing against)
[itex] Fhook-Fpress = 0 \,\Leftrightarrow \\ kx -10N = 0\\
kx = 10N [/itex]
 

Related Threads on Work done by variable force

  • Last Post
Replies
6
Views
15K
  • Last Post
Replies
3
Views
18K
Replies
4
Views
10K
  • Last Post
Replies
3
Views
2K
Replies
8
Views
1K
  • Last Post
Replies
4
Views
889
  • Last Post
Replies
1
Views
4K
Replies
4
Views
2K
Replies
12
Views
16K
Replies
5
Views
4K
Top