Friction problem involving a block and pulley on a ramp....

In summary, the problem is to find the minimum weight of block B needed to start the motion of block A up the inclined plane. The angle of friction between the block and the incline is 15° and the coefficient of friction is represented by μ. The resistive force of friction is represented by Fr. The key to solving this problem is to analyze the forces on block A and ensure that the net force is not 0, which will cause A to start moving. The diagram provided does not accurately represent the problem, as it shows friction acting both up and down the plane. Without friction, the block would move in a certain direction, so the friction will act in the opposite direction to balance out the forces.
  • #1
leojun
26
0

Homework Statement


In the system, find minimum weight of the block 'B' to start the motion of the block 'A'
up the plane.weight of block 'A' 10 KN. The angle of friction for the block and the incline,between the pulley and the string may be assumed as 15° (assume pulley is locked)
upload_2016-6-1_20-2-52.png

Homework Equations


Fr is the resistive force of friction.
μ is the coefficient of friction for the two surfaces (Greek letter "mu")
N is the normal or perpendicular force pushing the two objects together.
μN is μ times N.
Friction_angle-300x210.png


The Attempt at a Solution


i don't know how to solve it:([/B]
 
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  • #2
The problem requires the "minimum" condition, so your job is to make "A" move forwards. Try to analyse the forces on A. If the net force is not 0, then A will start to move.
 
  • #3
Your diagram is not correct for this problem. Perhaps you copied it from a different one.
It seems to show friction acting both up and down the plane. I assume it intends to show friction up the plane balancing the component of gravity down the plane, so Ffriction=m g sin(θ). But that is not the situation in this thread.
Without friction, which way would the block move? So which way will the friction act?
 

1. What is friction and how does it affect the block and pulley on a ramp?

Friction is a force that opposes the motion of two surfaces in contact. In the case of a block and pulley on a ramp, friction can cause the block to resist sliding down the ramp or the pulley to resist rotating. This can affect the overall motion and stability of the system.

2. How can friction be calculated in this scenario?

The force of friction can be calculated using the formula F = μN, where F is the force of friction, μ is the coefficient of friction, and N is the normal force between the two surfaces. The coefficient of friction depends on the materials and surface conditions of the block, pulley, and ramp.

3. Is there a way to reduce friction in this system?

Yes, there are several ways to reduce friction in this scenario. One way is to use lubricants, such as oil or grease, to make the surfaces smoother and reduce the coefficient of friction. Another way is to use materials with lower coefficients of friction, such as Teflon or nylon.

4. How does the angle of the ramp affect the friction in this problem?

The angle of the ramp can greatly affect the friction in this problem. As the angle increases, the normal force between the surfaces increases, resulting in a higher force of friction. This can make it more difficult for the block to slide down the ramp or for the pulley to rotate.

5. Can friction be completely eliminated in this scenario?

No, friction cannot be completely eliminated in this scenario. It is a fundamental force that always exists between two surfaces in contact. However, it can be reduced to a certain extent using the methods mentioned above.

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