Angular momentum and tension of string

In summary, the problem involves a 3kg puck revolving on a frictionless table at the end of a 50cm string. The puck's angular momentum is 3kg (m^2/s) and the question asks for the tension in the string. To solve, the formula for angular momentum (L= mrv) is used to find the velocity of the puck, which is then used in the formula for centripetal force (F=mv^2/r) to calculate the tension. However, there was an error in the calculation as the radius should be 0.50m, not 0.25m.
  • #1
guru
38
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?
 
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  • #2
r should be 0.50 m, not 0.25.
 
  • #3
I agree with arildno, the string is acting as the radius of the circle itself, not as the diameter :smile:
 

Related to Angular momentum and tension of string

1. What is angular momentum?

Angular momentum is a measure of the rotational motion of an object. It is determined by the mass, velocity, and distance from the axis of rotation.

2. How is angular momentum related to tension of string?

In a system where a string is attached to an object and is being pulled in a circular motion, the tension of the string is directly proportional to the angular momentum of the object. This means that as the tension of the string increases, so does the object's angular momentum.

3. How does the length of the string affect angular momentum?

The length of the string has an inverse relationship with the angular momentum of the object. This means that as the length of the string increases, the angular momentum decreases, and vice versa.

4. Can tension of a string affect the direction of angular momentum?

Yes, tension of a string can affect the direction of angular momentum. If the tension is applied at an angle to the axis of rotation, it will cause the angular momentum to change direction.

5. What is the formula for calculating angular momentum?

The formula for calculating angular momentum is L = Iω, where L is the angular momentum, I is the moment of inertia, and ω is the angular velocity.

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