Calculating Acceleration and Tension in a Pulley System

  • Thread starter Thread starter Nash77
  • Start date Start date
  • Tags Tags
    Pulley Two masses
AI Thread Summary
The discussion focuses on calculating the acceleration and tension in a pulley system involving two blocks and a pulley. Initially, the acceleration was calculated as 0.80 m/s², but this did not consider the pulley's mass or its effect on the system's dynamics. The revised formula for acceleration incorporates the mass of the pulley, resulting in a new value of 0.533 m/s². Participants express confusion about the inclusion of the pulley's mass in the calculations and seek clarification on the reasoning behind it. Understanding the role of the pulley's mass is crucial for accurate calculations in such systems.
Nash77
Messages
9
Reaction score
0
Please refer to problem VI here:

http://www.physics.ohio-state.edu/~dongping/phys131_winter2011/phys131/final-exam-practice-2011.pdf

Use 10 for gravity if needed.

Homework Statement



1. When the system is released from rest, what is the magnitude of the blocks' acceleration?
2. What are the tensions in the part of the cord that supports the heavier block and the lighter block, respectively?
3. What is the magnitude of the pulley's angular acceleration?


Homework Equations



F1 = m1a = m1g - T
F2 = m2a = T - m2g



The Attempt at a Solution



So, we used the equations above, added both equations together to eliminate T, then solved for a.

m1a + m2a = m1g - T + T - m2g
m1a + m2a = m1g - m2g
a(m1 + m2) = g(m1 - m2)
a = g(m1 - m2)
-----------
(m1+m2)

a = 0.80 m/s^2

But this gave an acceleration of 0.80 m/s^2 and it never took into account the mass or acceleration of the pulley. How do we incorporate that information? Our TA emailed us, saying the answer should be 0.533 m/s^2??
 
Physics news on Phys.org
So, we found a new way to solve for acceleration and it works, just not sure why.

a = g(m1 - m2)
---------------
(m1+m2+1/2MP)

^^ where MP = mass of the pulley.

Why did we add in the 1/2 mass of the pulley to solve?
 

Thread 'Rolling without slipping on a curved surface'

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 .
View full post »

Thread 'Struggling to understand the concept of this question (ice cube in water optics question)'

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...
View full post »

Similar threads

Accelerating pulleys (3 pulleys and 3 masses)
Replies
5
Views
2K
Halliday, Resnick & Krane Chapter 5: Force on Pulley
Replies
1
Views
2K
Angular Acceleration and Linear Acceleration of a Pulley
Replies
4
Views
2K
Block-pulley system and rotational dynamics
Replies
5
Views
5K
Acceleration and Tension in Multiple Pulleys
Replies
7
Views
8K
What if check: Am I calculating tension wrong?
Replies
3
Views
2K
Calculating tensions and acceleration
Replies
10
Views
2K
3 pulleys - 2 masses on incline plane
Replies
35
Views
4K
Problem with two pulleys and three masses
3
Replies
102
Views
7K
Two blocks on a plane with a pulley
Replies
11
Views
2K

Hot Threads

Recent Insights

Back
Top