Sliding blocks and a string problem

In summary, the problem involves two blocks, A and B, with weights 3w and w, respectively. Block A is sliding down an inclined plane at a constant speed while block B rests on top and is attached to the wall by a cord. The coefficient of kinetic friction is the same between A and B and between A and the inclined plane. The forces acting on block A are NB, wA, and static friction between A and the inclined plane. The normal force between A and B is not mentioned, but the normal force between A and the inclined plane is. The presence of friction between blocks A and B is questioned, but the normal force between them is listed.
  • #1
Anatalbo
4
0

Homework Statement


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Block A, with weight 3w, slides down an inclined plane S of slope angle 36.9 degrees at a constant speed while plank B, with weight w, rests on top of A and is attached by a cord to the wall. If the coefficient of kinetic friction is the same between A and B and between S and A, determine its value.

Homework Equations

The Attempt at a Solution


I have some trouble doing the free body diagram for A, I assume the forces acting on said block are: NB, wA, static friction between S and A, but I am not sure about the friction between A and B.
 
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  • #2
Anatalbo said:
the forces acting on said block are: NB, wA, static friction between S and A, but I am not sure about the friction between A and B.
You mention static friction between S and A, but not the normal force there.
Why do you doubt friction between A and B, yet have listed "NB", which I take to be the normal force between A and B?
 

1. What is the sliding blocks and a string problem?

The sliding blocks and a string problem, also known as the "block and tackle" problem, is a classic physics problem that involves a set of connected blocks and a string, and requires finding the tension in the string and the acceleration of the blocks.

2. What are the assumptions made in the sliding blocks and a string problem?

The problem assumes that all the blocks are connected by a non-stretchable string, and that there is no friction between the blocks or the string. It also assumes that the pulleys or other devices used to change the direction of the string are massless and frictionless.

3. How do you solve the sliding blocks and a string problem?

To solve the problem, you first need to draw a free body diagram for each block and apply Newton's laws of motion to each block. Then, you can use the equations of motion to find the acceleration of the blocks and the tension in the string. It is also helpful to label the forces acting on each block and use the principle of conservation of energy to check your answer.

4. Can the sliding blocks and a string problem be solved using calculus?

Yes, the problem can be solved using Newton's second law and the equations of motion, which are derived from calculus. However, it is also possible to solve the problem using basic algebra and trigonometry.

5. Are there any real-life applications of the sliding blocks and a string problem?

Yes, the sliding blocks and a string problem has many real-life applications, such as in elevators, cranes, and other systems that use pulleys and strings to lift heavy objects. It is also used in the design of various mechanical systems, such as bicycles and gears.

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