How Do Spring Force, Static Friction, and Normal Force Interact?

In summary, the conversation discusses a problem with a block on a spring and how to calculate the friction force. The correct relationship is μN - mg = 0, not Fs - mg = 0. To find the friction force, you need to multiply the normal force (N) by the coefficient of friction (μ). Turning the picture 90 degrees clockwise may help understand the problem better.
  • #1
yesmale4
41
1
Homework Statement
The coefficient of static friction can be determined using the following procedure. A block is held against a vertical wall by compressing a spring attached to the block as shown below. If the spring has a spring constant = 531 N/m and requires a compression of 3.7 cm to just keep the block from slipping, what is the static friction coefficient between the wall and the 4.5 kg block?
Relevant Equations
f=x*k
kl.png

kk.jpg


i would like to understand why my answer is incorrect and how i need to solve this problem
 
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  • #2
Looks to me like you've got things upside down. Given that spring compression, what's the force pushing on the block? How does that relate to the friction?
 
  • #3
Based on this relation,

(fs)max = μs N

the value of μs must be greater than 1 in this case, as (fs)max > N
 
  • #4
Doc Al said:
Looks to me like you've got things upside down. Given that spring compression, what's the force pushing on the block? How does that relate to the friction?
Fspring= x*k = 0.037*531
i don't see how the friction is relate because the only force is Fs-mg=0
 
  • #5
Lnewqban said:
Based on this relation,

(fs)max = μs N

the value of μs must be greater than 1 in this case, as (fs)max > N
i understand so how i need to change my calculations to get to the right answer
 
  • #6
yesmale4 said:
Fspring= x*k = 0.037*531
That's correct.
yesmale4 said:
i don't see how the friction is relate because the only force is Fs-mg=0
If by Fs you mean the spring force, that is incorrect. The only vertical forces acting on the block are gravity and friction (not the spring force). The spring force is like the normal force (N). To get the friction you multiply by μ. Then you'll have μN - mg = 0. Solve for μ. (You had it upside down.)
 
  • Like
Likes Lnewqban
  • #7
yesmale4 said:
i understand so how i need to change my calculations to get to the right answer
Perhaps if you turn the picture 90 degrees clockwise, you could see the more traditional problem.
Please, refer to post #6 above.
 
  • #8
Doc Al said:
If by Fs you mean the spring force
More likely it stands for the static friction force.
If so, @yesmale4 , what are the relationships between:
##F_{spring}, F_s, N##?
 

FAQ: How Do Spring Force, Static Friction, and Normal Force Interact?

What is "Blockage Held by Spring"?

"Blockage Held by Spring" is a term used in engineering and mechanics to describe a type of mechanism that uses a spring to hold a blockage in place.

How does a "Blockage Held by Spring" work?

This mechanism works by using the force of a spring to hold a blockage, such as a valve or gate, in a specific position. When the spring is compressed, it applies a force to the blockage, keeping it in place. When the spring is released, the blockage can move freely.

What are the advantages of using a "Blockage Held by Spring"?

One advantage of this mechanism is that it allows for precise control over the movement of the blockage. The force of the spring can be adjusted to hold the blockage in different positions, allowing for fine-tuning of the system. Additionally, this mechanism is simple and cost-effective to implement.

What are some common applications of "Blockage Held by Spring"?

This mechanism is commonly used in various industries, such as automotive, aerospace, and manufacturing. It can be found in systems that require precise control over the flow of fluids or gases, such as in engines, pumps, and valves.

Are there any potential drawbacks to using a "Blockage Held by Spring"?

One potential drawback is that the spring may wear out over time and need to be replaced. Additionally, if the spring is not properly calibrated, it may not provide enough force to hold the blockage in place. Regular maintenance and proper calibration can help mitigate these potential issues.

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