HW: Newton's Second Law and Angles

AI Thread Summary
The discussion centers on understanding how the angle (theta) of a thread supporting a mass relates to the acceleration of a system, as described by Newton's Second Law. The user initially struggled with drawing a free body diagram to analyze the forces acting on the system, particularly the tension in the string. After further exploration and reviewing similar problems, they derived equations for the forces in both the x and y directions, leading to a relationship between theta and acceleration. The user confirmed their solution after the relevant diagram was approved for viewing. The thread concludes with the user feeling satisfied that they have solved the problem.
Aerodin
Messages
5
Reaction score
0
[SOLVED] HW: Newton's Second Law and Angles

Homework Statement


The system shown in the figure can be used to measure the acceleration of the system. An observer riding on the platform measures the angle (theta) that the thread supporting the light all makes with the vertical. There is no friction anywhere.

How is (theta) related to the acceleration of the system? (Mathematical/with an equation)

Homework Equations


F=ma

The Attempt at a Solution



Well, after working on this for at least an hour, I'm thinking that to figure out what the angle has to be I have to use the idea of drawing a free body diagram of the ball/angle part of the diagram or something. I'm really having some serious trouble doing this so any help would be awesome. Thanks!

Edit: I just figured out that if I do draw the whole free body diagram, it looks like i may be able to find how the angle is related. However, in order to do so, I need to know what the tension force of the string that the ball is on would be, and that's where I'm getting stuck.
 

Attachments

  • figure.jpg
    figure.jpg
    19 KB · Views: 1,102
Last edited:
Physics news on Phys.org
So I just read a couple of other threads about similar problems as this, and I think I figured out the right answer, but I'd like someone to check it if they can...

Pretty much, I found the forces on the hanging ball in terms of x and y (like the forces in the x direct and the forces in the y direction), and then solved for theta... if this is right, then

Ax=gcos(theta)
Ay=g-gsin(theta)
 
Last edited:
Hey guys, I don't mean to be pesky, and I know this probably wasn't the best time to post this, but this thing is due in the morning and i just want to see if it's correct or not... thanks :)
 
Hard to say, while your attachment is still pending approval and we can't see it. Can you try and describe the system in words?
 
ohh ok sry about that. Pretty much, there are 2 masses. One is hanging off of a pully and the other is on a horizontal surface with no friction attached by that same string on the same pully. On the second mass (the one on the horizontal surface), there is a pole with a massless ball hanging. The angle that this ball is at is supposed to be related to the acceleration of the system.

Update: The picture looks like it just got approved, so that should be a lot more helpful.
 
Last edited:
Well, I think I figured it out, so i'll leave this as solved.
 

Thread 'Errors and significant figures'

I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
View full post »
Thread 'A cylinder connected to a hanging mass'

Thread 'A cylinder connected to a hanging mass'

Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
View full post »

Similar threads

Convert to Center of Mass Reference Frame
Replies
9
Views
1K
Having a hard time learning Newton's 2nd law
Replies
5
Views
2K
Calculating acceleration of a prism and block connected to a wall through a rope and pulley
Replies
4
Views
329
Is it friction or tension acting on the person hanging on a rope?
Replies
4
Views
1K
Newton's second law (My turtle named Newton being accelerated)
Replies
9
Views
2K
Finding an angle with Newton's Second Law
Replies
3
Views
4K
Newton's Second Law (Pulley Sustem)
Replies
3
Views
2K
Finding angles with Bragg's Law
Replies
20
Views
2K
Newton's 2nd law with oscilations
Replies
17
Views
2K
Explanation for Newton II giving negative mass in my Physics lab results please
Replies
44
Views
3K

Hot Threads

Recent Insights

Back
Top