Pulley, friction, acceleration

In summary, the conversation discusses the acceleration of two blocks on a surface with and without friction. The first block has an acceleration of 4.9m/s/s without friction and 3.92m/s/s with a coefficient of kinetic friction of 0.2. The second block has a similar acceleration of 4.9m/s/s without friction, but with a slightly lower acceleration of 3.92m/s/s when taking into account the friction coefficient. The conversation also mentions the use of a linear model to calculate the forces and acceleration.
  • #1
joel amos
104
0

Homework Statement


http://imageshack.us/a/img703/7864/physicsb.png
From the image above:
a) If there is no friction between A and surface, what is the blocks' acceleration?
b) With coefficient of 0.2?
 
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  • #2
What do you think the acceleration would be?
 
  • #3
hi joel! :wink:

show us what you've tried, and where you're stuck, and then we'll know how to help! :smile:
 
  • #4
So I found acceleration to be 4.9m/s/s without friction and 3.92m/s/s with a coefficient of kinetic friction of 0.2. Is this correct?
 
  • #5
4.9 [itex] m/s^2 [/itex] is correct for the acceleration without friction. You could figure that out just by looking at the diagram because you know that if the force of gravity pulling down 1 block pulls down twice that mass, then the system will accelerate at half of the acceleration for one block. In your case, it's half of g.

For the acceleration of the block including friction, I'm not totally sure, but 3.92 [itex] m/s^2 [/itex] sounds reasonable. You probably got it.
 
  • #6
hi joel! :smile:

(just got up :zzz:)

yes, howie8594 :smile: is correct …

you can pretend everything is in a line …

force 9.8, mass 2, -> acceleration 4.9​

similarly for the friction µ = 0.2 …

force 9.8 * (1 - 0.2), mass 2, -> acceleration 4.9*0.8 :wink:
 
  • #7
Thanks a lot for your help and confmirations. Highly appreciated :)
 

Related to Pulley, friction, acceleration

1. How does a pulley work?

A pulley is a simple machine that consists of a wheel with a groove around the outside and a rope or chain that runs along the groove. When a force is applied to one end of the rope, the pulley can lift or move a load on the other end of the rope. This is because the pulley changes the direction of the force, making it easier to lift the load.

2. What is the role of friction in pulley systems?

Friction plays a crucial role in pulley systems by providing the necessary grip between the rope and the pulley. Without friction, the rope would simply slip off the pulley and the system would not work. However, too much friction can also be a problem as it can cause the rope to wear out quickly and make the system less efficient.

3. How does friction affect acceleration?

Friction can either increase or decrease acceleration depending on the direction of the force and the type of surface involved. When the force and friction are in opposite directions, friction can slow down or stop the movement of an object. On the other hand, when the force and friction are in the same direction, friction can help increase the acceleration of an object.

4. Can pulleys be used to increase or decrease acceleration?

Yes, pulleys can be used to increase or decrease acceleration depending on the arrangement of the pulley system. In a fixed pulley, the load moves the same distance as the force applied, so the acceleration remains the same. However, in a movable pulley, the load moves twice as far as the force applied, resulting in a greater acceleration. In a block and tackle pulley system, the load can be lifted with less force, but it also moves a greater distance, resulting in a decrease in acceleration.

5. What factors affect the acceleration of an object in a pulley system?

The acceleration of an object in a pulley system is affected by the mass of the object being lifted, the force applied to the rope, the number of pulleys in the system, and the amount of friction present. In general, a lower mass, higher force, and lower friction will result in a greater acceleration in a pulley system.

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