Acceleration involving Newton's 2nd law

Click For Summary

Homework Help Overview

The problem involves a system of boxes connected by ropes, where the original poster seeks to determine the acceleration of the boxes using Newton's second law. The scenario includes a box on a platform with two hanging boxes, and the mass values are provided.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • The original poster attempts to apply Newton's second law but expresses confusion about the next steps after setting up their equations. Some participants question the presence of friction and suggest clarifying the diagram for better understanding.

Discussion Status

Participants are exploring different approaches to the problem, with some suggesting a more detailed application of Newton's second law while others advocate for a simpler, intuitive method. There is no explicit consensus on the best approach, but guidance has been offered regarding the application of force equations.

Contextual Notes

There is mention of potential complications due to multiple tension forces and the need for a diagram, which may indicate that visual representation is crucial for understanding the problem setup. The original poster's reference to a loop in their reasoning suggests possible missing information or assumptions that need clarification.

man_in_motion
Messages
11
Reaction score
0

Homework Statement


There is a box on a platform with mass 3.5kg and it has two ropes connected to it. On the end of each of these ropes are 2 other boxes hanging off the table (so only F_y component). One box is 2.5kg and the other is 1.5kg. I need to find the acceleration of all the boxes.

the answer is 1.3m/s^2 for all of them

Homework Equations



F_net=ma
F_g=mg

The Attempt at a Solution


a_box1=F_net/m=((m_1)(g)-a_box2)/m

I don't know how to proceed from here because I end up going in a loop
 

Attachments

Last edited:
Physics news on Phys.org
It takes a long time to get attachments approved. Can you describe the diagram?
Or you could put it up on a photo site like photobucket and post a link to it.
Is there friction in this question?
 
I see students posting complicated solutions with several tension forces, but I just do it by eye. There is an extra kg hanging on the right, so it will go right and the acceleration is
a = F/M where the force is the mg on the 1 kg and the M is the total mass.
 
Nothing wrong with "doing it by eye" in one step. But I strongly suggest you also do it the long way, by applying Newton's 2nd law to each mass. That's the method that will allow you to solve more complicated problems, so you might as well learn how to use it on this simpler one.

Write a Newton's 2nd law force equation for each mass. Combine those three equations and you'll be able to solve for the acceleration and the two rope tensions.
 

Similar threads

  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 42 ·
2
Replies
42
Views
6K
  • · Replies 38 ·
2
Replies
38
Views
5K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 5 ·
Replies
5
Views
4K
Replies
6
Views
4K
Replies
4
Views
1K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 2 ·
Replies
2
Views
5K