Understanding Spring Forces: Net Force and Spring Scale Readings

  • Thread starter Thread starter turdferguson
  • Start date Start date
  • Tags Tags
    Forces Spring
AI Thread Summary
In a scenario with a spring scale on a frictionless surface, two equal and opposite horizontal forces of 10 N are applied, resulting in a net force of 0 N, not 20 N. The spring scale measures the tension in the spring, which reflects the force applied to compress or stretch it, resulting in a reading of 10 N. The discussion emphasizes that forces are vectors, and direction is crucial in determining net force. It is clarified that a spring cannot be compressed or stretched by applying force to only one end. Understanding these principles is essential for accurately interpreting spring scale readings.
turdferguson
Messages
312
Reaction score
0
I just want to quickly check something. A spring scale lies horizontally on a frictionless surface. A horizontal force of 10 N to the right is applied to the top of the scale and another horizontal force of 10 N to the left is applied to the bottom.

1. The net force is ___ obviously 20 N

2. The reading on the spring scale will read ___ I am inclined to think that it would only be 10 N. The situation would be the same if the spring was attached to a wall. Am I right? Afterall, they wouldn't ask the same question twice
 
Physics news on Phys.org
turdferguson said:
1. The net force is ___ obviously 20 N
This is incorrect. Rethink this: what's the net force on the spring scale? Recall that forces are vectors--direction counts.

2. The reading on the spring scale will read ___ I am inclined to think that it would only be 10 N. The situation would be the same if the spring was attached to a wall. Am I right?
Yes, you are right. The spring scale reads the tension in the spring, which is 10 N.
 
Doc Al said:
This is incorrect. Rethink this: what's the net force on the spring scale? Recall that forces are vectors--direction counts.


Yes, you are right. The spring scale reads the tension in the spring, which is 10 N.

I saw this question before and it got me thinking, I do not really understand it. The spring is being compressed by two forces. Now if the reading is based on the fact that two equal and opposite forces will always act on the spring and then it takes the size of these forces that is okay.

I still cannot seem to get over the fact that there are two 10N forces compressing the spring.
 
ponjavic said:
I still cannot seem to get over the fact that there are two 10N forces compressing the spring.
If you can figure out a way to compress (or stretch) a spring by pushing (or pulling) on one end only, I'd like to see it. (Won't happen!)

The spring scale measures the degree of compression (or elongation) which is proportional to the compression force (or stretching force).
 
Doc Al said:
If you can figure out a way to compress (or stretch) a spring by pushing (or pulling) on one end only, I'd like to see it. (Won't happen!)

The spring scale measures the degree of compression (or elongation) which is proportional to the compression force (or stretching force).
That's actually what I was trying to do :D
 
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
View full post »

Similar threads

Distribution of Energy when work is done on a system of 2 masses connected by a spring
Replies
17
Views
2K
Why Isn't the Spring Force Sum of Both Ends?
Replies
5
Views
1K
Why can we move the spring with constant speed when we apply a force?
Replies
29
Views
2K
Calculating Net Force of 3 Blocks in an Elevator
Replies
9
Views
2K
Springs and Pulleys - Force analysis
Replies
18
Views
1K
Force transmitted to a block in viscous fluid through a spring, cord, and pulley
Replies
6
Views
825
A block dropping onto a spring system
2
Replies
58
Views
2K
How Does Spring Force Affect Net Force in Physics?
Replies
3
Views
1K
Problem with when to use Force and Energy. What compresses spring/
Replies
3
Views
1K
An error made in a kinematics question about a spring launcher?
Replies
16
Views
1K

Hot Threads

Recent Insights

Back
Top