Angular momentum and tension of string

AI Thread Summary
The problem involves a 3kg puck revolving in a circle with a radius of 0.50m, attached to a string. The angular momentum is given as 3kg(m^2/s), leading to the calculation of linear velocity using the formula L = mrv. The initial calculation mistakenly used a radius of 0.25m, resulting in an incorrect tension value. The correct tension in the string, considering the proper radius, is calculated to be 192N. The discussion emphasizes the importance of using the correct radius for accurate results.
guru
Messages
38
Reaction score
0
This problem is baffling me.

A 3kg puck revolves in a circle on a frictionless table at the end of a 50cm long string. The puck's angular momentum is 3kg (m^2/s). What is the tension in the string?

This what I did
L= mrv
therefore
3kg*.25m*v = 3kgm^2/2
v=4m/s
F=(mv^2)/r
(3kg*16m/s)/(.25m) = 192N

is this right?
 
Physics news on Phys.org
r should be 0.50 m, not 0.25.
 
I agree with arildno, the string is acting as the radius of the circle itself, not as the diameter :smile:
 

Thread 'Derivation of Hamilton's Principle: Questions'

I have recently been really interested in the derivation of Hamiltons Principle. On my research I found that with the term ##m \cdot \frac{d}{dt} (\frac{dr}{dt} \cdot \delta r) = 0## (1) one may derivate ##\delta \int (T - V) dt = 0## (2). The derivation itself I understood quiet good, but what I don't understand is where the equation (1) came from, because in my research it was just given and not derived from anywhere. Does anybody know where (1) comes from or why from it the...
View full post »

Similar threads

I Understanding tension and centripedal force in a puck and weight
Replies
4
Views
2K
Angular momentum and when center of rotation is changed
Replies
3
Views
2K
Angular momentum and centripetal force
Replies
5
Views
7K
Confused about tension in strings
Replies
8
Views
2K
When to apply conservation of angular momentum?
Replies
13
Views
2K
I Time derivative of the angular momentum as a cross product
Replies
3
Views
1K
How does the velocity of a mass spun around a pencil change?
Replies
2
Views
1K
I Problem with understanding angular momentum
Replies
30
Views
3K
Difference between angular velocity and angular frequency
Replies
21
Views
19K
Using the angular momentum principle for 2 pucks
Replies
3
Views
2K

Hot Threads

Recent Insights

Back
Top