Pulley system problem: 6 Pulleys and 1 Mass

  • #1
david3305
9
1
Homework Statement
Find force F
Relevant Equations
m_1 = 5kg, g = 10 m/s^2
The following system is at rest with a block of mass m1 = 5kg, and a force F that is applied to the end of a string attached to the pulley system. Let g, the acceleration due to gravity equal to 10 (for simple calculations).

pulley1.jpg

My analysis is as follows:

I'll first label the strings Tsub1 and Tsub2, and each pulley in red P1 and P2 (in red):

pulley2.jpg


From here I'll make 3 free body diagrams:

m1:
pulley3.jpg

$$\begin{array}{rcl} & T_{1} = gm_{1} = 50N \\ \end{array}$$

then P1:
pulley5.jpg


$$\begin{array}{rcl} &T_{x} = 2T_{1} \end{array}$$

then P2:

pulley6.jpg


$$\begin{array}{rcl} &T_{x} = 2T_{2} \end{array}$$

From these equations we have that

$$\begin{array}{rcl} &T_{1} = T_{2} \end{array}$$

and therefore

$$\begin{array}{rcl} &T_{1} = T_{2} = F = 50N \end{array}$$
 
Last edited by a moderator:
Physics news on Phys.org
  • #2
Is there a question you wish to ask about this?
 
  • #3
Sorry, I just wanted to know if my reasoning is correct. Im just a simple man trying to figure out stuff on my own without any formal training. In fact, I didn't even took physics in highschool, back in the day it wasn't required on my 3rd world country.
 
  • Like
Likes berkeman
  • #4
david3305 said:
Sorry, I just wanted to know if my reasoning is correct. Im just a simple man trying to figure out stuff on my own without any formal training. In fact, I didn't even took physics in highschool, back in the day it wasn't required on my 3rd world country.
If you do/don't have formal training, your free body diagrams look well done/reasoned to me.
 
  • Like
Likes berkeman
  • #5
erobz said:
If you do/don't have formal training, your free body diagrams look well done/reasoned to me.
Thanks, thats Khan Academy and a bunch of youtube videos for you.
 
  • #6
david3305 said:
Sorry, I just wanted to know if my reasoning is correct. Im just a simple man trying to figure out stuff on my own without any formal training. In fact, I didn't even took physics in highschool, back in the day it wasn't required on my 3rd world country.
Your reasoning is correct. I wish that more of my students explained theirs as clearly as you did.
 
  • Like
Likes berkeman and erobz

Similar threads

Replies
15
Views
4K
Replies
18
Views
379
Replies
40
Views
3K
Replies
10
Views
4K
Replies
22
Views
4K
Replies
4
Views
3K
Replies
8
Views
1K
Replies
4
Views
3K
Replies
12
Views
2K
Back
Top