Tension and centripital motion help

In summary, two blocks tied together with a string are spun around a center point. The coefficient of static friction between the blocks and the turntable is µs = 0.74, and the string is taut. The tension in the string is calculated using the same equations used to find the maximum rotational speed without slipping. The blocks have a mass of 35 g, and the maximum rotational speed without slipping is w = 12.7 rad/s.
  • #1
erogers4
5
0
Two identical blocks are tied together with a string and placed along the same radius of a turntable that is spinning about its center. The inner block is 3 cm from the center and the outer block is 6 cm from the center. The coefficient of static friction between the turntable and the blocks is µs = 0.74, and the string is taut.

I have determined that w = 12.7 rad/s

Now suppose that the blocks each have a mass m = 35 g. For the value of w you just found, what is the tension in the string?

For some reason, I cannot seem to get the right answer. SOMEONE PLEASE HELP!
 
Physics news on Phys.org
  • #2
Show your work and how you solved for the tension and we can take a look.
The same equations used to solve for [itex]\omega[/itex] (the maximum rotational speed without slipping) will include the tension.
 
  • #3
my equations i used were:
1) T - umg = m R1 w^2
2) -T - umg = m R2 w^2

i was able to get w, but then i plug values back in and its not accepting my answer for T as being correct. i have no idea what I am doing wrong. please help!
 
  • #4
For one thing, your signs are messed up in those equations. Choose a sign convention: for example, make towards the center positive, away from the center negative. Rewrite those equations accordingly. (The way they are written now, [itex]\omega^2[/itex] is negative!)
 
  • #5
ok i realized i typed in the wrong ones...i had those at first, the new ones are
1) -T + umg = m r1 w^2
2) T + umg = m r2 w^2

i believe that is how i got 12.7 for w (i have so much work here and half of it is wrong, I am not sure which is which anymore). I just tried solving for T though and it is still not right. ah I am so confused now!
 
  • #6
Ok maybe those equations aren't right either...I can't seem to get the 12.7 for w again, tho I know that is right. I have no idea what I'm doing anymore!
 
  • #7
Those equations are correct. Show how you solved for T and what you got.

(To find [itex]\omega[/itex], start by adding those two equations.)
 
  • #8
to find T i had:

T = umg - m r1 w^2
as well as
T = m r2 w^2 -umg

m=.035kg
r1=.03m
r2=.06m
w=12.7 rad/sec
u=.74
g=9.81

i plug those in and get
T=.0847

which apparently is right...i had that before i don't know y it wouldn't take it as being correct...thanks for all you help!
 

What is tension in relation to centripetal motion?

Tension is the force that is transmitted through a string, rope, or any other type of flexible connector when it is pulled tight by forces acting on either end. In centripetal motion, tension is the force that keeps an object moving in a circular path.

How is tension related to centripetal acceleration?

Tension is directly related to centripetal acceleration. The greater the tension in a string, the greater the centripetal acceleration of the object attached to the string.

What is the role of tension in the centripetal force equation?

In the centripetal force equation, tension is one of the forces acting on an object in circular motion. It is the force that is directed towards the center of the circle and is responsible for keeping the object moving in a circular path.

How does tension affect the speed of an object in centripetal motion?

The tension in a string or rope affects the speed of an object in centripetal motion by controlling the centripetal force. As the tension increases, the centripetal force increases, which in turn increases the speed of the object.

What happens to tension if the radius of the circle increases in centripetal motion?

If the radius of the circle increases in centripetal motion, the tension in the string or rope will decrease. This is because the centripetal force is inversely proportional to the radius, therefore a larger radius will result in a smaller tension force.

Similar threads

  • Introductory Physics Homework Help
Replies
1
Views
1K
Replies
19
Views
3K
  • Introductory Physics Homework Help
Replies
3
Views
1K
  • Introductory Physics Homework Help
Replies
3
Views
1K
  • Introductory Physics Homework Help
Replies
4
Views
2K
  • Introductory Physics Homework Help
Replies
4
Views
2K
  • Introductory Physics Homework Help
Replies
2
Views
2K
  • Introductory Physics Homework Help
Replies
9
Views
3K
  • Introductory Physics Homework Help
Replies
10
Views
2K
  • Introductory Physics Homework Help
Replies
24
Views
8K
Back
Top