Friction and a pulley

In summary, the system shown in the figure consists of blocks, a light frictionless pulley, and connecting ropes. The 9.0-kg block is on a smooth horizontal table while the 12-kg block has rough surfaces with a coefficient of kinetic friction of 0.30 between the block and the table. The 5.0-kg block accelerates downward when released and the question asks for its acceleration. After solving using the equations provided, the answer is determined to be 1.6 m/s^2. However, it is advised to refer to emailanmol's posts in the other thread for further clarification.
  • #1
algar32
89
1

Homework Statement



A system comprised blocks, a light frictionless pulley, and connecting ropes is shown in the figure. The 9.0-kg block is on a perfectly smooth horizontal table. The surfaces of the 12-kg block are rough, with \mu_k = 0.30 between the block and the table. If the 5.0-kg block accelerates downward when it is released, find its acceleration.

the figure looks like this picture (except M= 5kg):
http://www.cramster.com/answers-feb-11/physics/system-comprising-blocks-system-comprising-blocks-light-frictionless-pulle_1126069.aspx?rec=0

14 minutes ago
- 4 days left to answer.



Homework Equations





The Attempt at a Solution


I want to say it is 1.6 m/s^s but I am not sure If I did it right.
I just added the force friction to the force tension and then divided by the weights (9+5).
Not sure if this is correct or not.
 
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  • #2
Looks right to me.
 
  • #3
This is very similar to the earlier problem you asked.

Use those equations to find the answer :-)
 
  • #4
tal444 said:
Looks right to me.

EDIT: I was doing this question wrong earlier, refer to emailanmol's posts in your other thread.
 
  • #5


I would like to clarify that the question does not provide enough information to accurately determine the acceleration of the 5-kg block. We need to know the mass of the 9-kg block and the force applied to the 12-kg block in order to calculate the acceleration. Additionally, the direction of the frictional force needs to be taken into account as it may oppose the motion of the blocks and affect the acceleration. Without these details, it is not possible to provide a precise answer. I recommend reviewing the problem and providing all necessary information in order to accurately solve for the acceleration.
 

1. What is friction and how does it affect a pulley?

Friction is a force that opposes motion between two surfaces in contact. In a pulley system, friction can affect the efficiency and speed of the pulley by creating resistance and reducing the amount of force that can be transmitted through the system.

2. How can friction be reduced in a pulley system?

Friction can be reduced in a pulley system by using lubricants, such as oil or grease, between the moving parts of the pulley. Choosing materials with low coefficients of friction, such as Teflon or nylon, can also help reduce friction in a pulley system.

3. What is the advantage of using a pulley in a frictional system?

The advantage of using a pulley in a frictional system is that it can help to distribute and reduce the amount of frictional force acting on the system. This can make it easier to move objects or lift weights, as the force is spread out over multiple ropes or cables.

4. How can the amount of friction in a pulley system be calculated?

The amount of friction in a pulley system can be calculated using the formula F=μN, where F is the frictional force, μ is the coefficient of friction, and N is the normal force between the two surfaces in contact. The coefficient of friction can be determined by conducting experiments or consulting tables of frictional coefficients for different materials.

5. Can a pulley system ever be completely frictionless?

No, it is impossible to create a completely frictionless pulley system. Even with lubricants and low friction materials, there will always be some amount of friction present. However, the friction can be minimized to a negligible amount, making the system much more efficient.

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