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

AI Thread Summary
The discussion centers on the concept of tension in a string pulling a block along a surface at an angle. Participants clarify that the tension force is equal in magnitude and opposite in direction to the applied force. There is confusion regarding the relationship between force and length, with corrections emphasizing that forces should not be equated to lengths. The importance of setting up equations for vertical and horizontal components of net force is highlighted, particularly when acceleration is zero. Additionally, the use of LaTeX for writing equations is encouraged for clarity in future discussions.
Memo
Messages
35
Reaction score
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
 
Last edited:
Physics news on Phys.org
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.
 
  • Like
  • Care
Likes MatinSAR and Memo
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!
 
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.
 
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
Back
Top