Do all masses in a pulley have the same acceleration?

AI Thread Summary
In pulley systems, all masses connected by a single, inextensible string experience the same acceleration due to the constraints of the cable. When analyzing such systems, it's effective to calculate the net force of the entire system and apply F=ma using total mass and net force. However, in some configurations, individual masses may have different accelerations depending on the system setup. For example, one mass may accelerate upward while another accelerates downward, potentially at different rates. Understanding the relationship between the masses' accelerations is crucial, often requiring free body diagrams to clarify their interactions.
Balsam
Messages
226
Reaction score
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.
 
Physics news on Phys.org
All the mass have the same acceleration, if not that would mean that the cable connecting 'em would change it's lenght
 
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
 
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 .
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...

Similar threads

Replies
30
Views
3K
Replies
5
Views
928
Replies
10
Views
5K
Replies
22
Views
6K
Replies
18
Views
811
Back
Top