Pulling a block along a surface using a string inclined at an angle

  • #1
Memo
35
3
Homework Statement
A block with a weight of P is being pulled by a string of length l at a constant rate and an angle. The distance between the tip of the block to the surface is h. (see the photo below)
Find the kinetic coefficient of friction (the string is attached to the centre of the block)
Answer hint: k=(F*sqrt(l^2-h^2))/(Pl-Fh)
Relevant Equations
f=k*N
00001 (1).jpg

00001.jpg
 
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  • #2
Memo said:
The tension force along the string is equal in magnitude and opposite in direction to the force being applied
I don't understand this. The tension is ##\vec F## and has the same magnitude and direction.
Memo said:
Can I put Fx=sqrt(l^2-h^2) and Fy=h?
No you cannot. It says that a force is equal to a length which is never true.

Try getting two equations, saying that vertical and horizontal components of the net force are zero which is always true when the acceleration is zero.
 
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  • #3
kuruman said:
I don't understand this. The tension is ##\vec F## and has the same magnitude and direction.

No you cannot. It says that a force is equal to a length which is never true.

Try getting two equations, saying that vertical and horizontal components of the net force are zero which is always true when the acceleration is zero.
I watched a somewhat relevant YouTube video and saw there was also the tension force, so I included it. But I've my problems, thank you so much!
 
  • #4
Your solution looks correct. For future reference, please don't edit the original post because it can be confusing to people who have seen it and are trying to respond to it. Corrections or additions to the first post should be posted separately.

Also, you are encouraged to use LaTeX to write equations. It's a useful skill and makes everybody's life much easier. Click on the link "LaTeX Guide" (lower left above "Attach files") to learn how.
 
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1. How does the angle of inclination affect the force required to pull the block?

The force required to pull a block along a surface using a string inclined at an angle is directly proportional to the angle of inclination. As the angle increases, the force required to pull the block also increases. This is because a larger angle creates a larger component of the force acting against the direction of motion, making it more difficult to move the block.

2. What factors influence the frictional force between the block and the surface?

The frictional force between the block and the surface is influenced by several factors, including the type of surface, the roughness of the surface, and the weight of the block. A rougher surface and a heavier block will result in a higher frictional force, while a smoother surface and a lighter block will result in a lower frictional force.

3. How does the mass of the block affect the force required to pull it along the surface?

The mass of the block does not directly affect the force required to pull it along the surface using a string inclined at an angle. However, a heavier block will have a greater weight, which can increase the frictional force between the block and the surface, making it more difficult to pull.

4. Is there a minimum angle of inclination required to pull the block along the surface?

Yes, there is a minimum angle of inclination required to pull the block along the surface. This angle is known as the angle of repose and is the steepest angle at which the block will remain stationary on the surface without sliding down. If the angle of inclination is below the angle of repose, the block will not move.

5. How does the coefficient of friction affect the force required to pull the block?

The coefficient of friction is a measure of the roughness of the surface and the materials in contact. A higher coefficient of friction means there is more resistance between the block and the surface, resulting in a higher force required to pull the block. Conversely, a lower coefficient of friction means there is less resistance and a lower force is required to pull the block.

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