Do all masses in a pulley have the same acceleration?

In summary, when solving for acceleration in pulley problems, it is important to consider whether the masses in the system have the same acceleration or not. This can be determined by making a free body diagram for each mass and considering the condition that the length of the string must be constant. In some cases, all masses may have the same acceleration, while in others, their accelerations may differ.
  • #1
Balsam
226
8

Homework Statement


The way my teacher makes us solve for accelleration in pulley problems is by calculating the net force of the system as a whole and then using F=ma, with the total mass and total net force. Are you supposed to solve for something like accelleration seperately for each mass or do all masses in a pulley have the same accelleration?

Homework Equations


F=ma

The Attempt at a Solution


Does it make sense to solve for the accelleration of the system as a whole or of the separate masses? I'm not sure.
 
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  • #2
All the mass have the same acceleration, if not that would mean that the cable connecting 'em would change it's lenght
 
  • #3
Balsam said:

Homework Statement


The way my teacher makes us solve for accelleration in pulley problems is by calculating the net force of the system as a whole and then using F=ma, with the total mass and total net force. Are you supposed to solve for something like accelleration seperately for each mass or do all masses in a pulley have the same accelleration?
If all masses have the same acceleration, depends on the problem.
In the figure on the left, the masses have the same acceleration, A upward and B downward. On the right, the accelerations are not the same. The upward acceleration of A is twice the downward acceleration of B. Make a free body diagram for each mass and find the relation of their accelerations from the condition that the length of the string must be constant.

upload_2016-3-20_6-36-41.png
 

FAQ: Do all masses in a pulley have the same acceleration?

What is a pulley?

A pulley is a simple machine that consists of a wheel with a groove around its circumference, over which a rope or cable can be pulled. It is used to change the direction of a force or to lift and move objects.

How do I solve pulley problems?

To solve a pulley problem, you need to understand the concept of mechanical advantage, which is the measure of how much a machine multiplies the force applied to it. You also need to know the relationship between the number of ropes supporting a load and the mechanical advantage of the pulley system.

What is the difference between a fixed and a movable pulley?

A fixed pulley is attached to a stationary object, while a movable pulley is attached to the load being lifted. A fixed pulley changes only the direction of the force, while a movable pulley increases the mechanical advantage by reducing the amount of force needed to lift the load.

What is the ideal mechanical advantage of a pulley?

The ideal mechanical advantage of a pulley is the number of ropes supporting the load. For example, a pulley system with 3 ropes supporting a load has an ideal mechanical advantage of 3.

What are some common types of pulley systems?

Some common types of pulley systems include the fixed pulley, movable pulley, compound pulley, and block and tackle system. Each type has a different mechanical advantage and is used for different purposes depending on the load and the desired force.

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