Angular Momentum Horizontal Metallic Bob

In summary, the problem involves a small metallic bob suspended from the ceiling and set in motion in a horizontal circle, causing the thread to describe a cone. The task is to calculate the magnitude of the angular momentum of the bob about a vertical axis through the supporting point. The given values are: angle of 29 degrees, string length of 2.4 meters, and mass of 9 kg. To solve the problem, the radius can be found using the string length and angle, and the velocity can be found by equating the centripetal acceleration to the acceleration produced by the circular motion.
  • #1
RivalDestiny
4
0

Homework Statement



A small metallic bob is suspended from the
ceiling by a thread of negligible mass. The
ball is then set in motion in a horizontal circle
so that the thread describes a cone. Calculate
the magnitude of the angular momentum of the
bob about a vertical axisthrough the supporting point.

angle: 29
string length: 2.4 m
mass: 9 kg

Homework Equations



L= r x mv

The Attempt at a Solution



mass is given in the problem

radius can be found by:

(string length) * sin29 = r

I don't know how to find the velocity...do we first have to find the angular velocity and convert that over to linear velocity?
 
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  • #2
You have to draw a force diagram on the bob. It has a force of mg pointing down. There is a tension force T directed along the string. The vertical components of those two forces must cancel. That leaves you with a horizontal component of T pointing towards the center of the circle it's rotating in. Using F=ma that you can find the acceleration of bob towards the center of the circle. Equate that to the acceleration you produced by the circular motion.
 
  • #3
alright, so I found the centripetal acceleration. Would I equate that to:

a=v^2/r?

r being the (L)*sin29..

then that would be v?
 

1. What is Angular Momentum?

Angular momentum is a physical quantity that describes the rotational motion of an object. It is a measure of the amount of rotational energy an object possesses.

2. How is Angular Momentum calculated?

Angular momentum is calculated by multiplying the moment of inertia of an object (a measure of its resistance to rotation) by its angular velocity (the rate at which it rotates around an axis).

3. What is a Horizontal Metallic Bob?

A horizontal metallic bob is a type of pendulum consisting of a metal weight or bob suspended from a horizontal arm or string. It is commonly used in physics experiments to demonstrate principles such as oscillation and energy conservation.

4. How does Angular Momentum affect a Horizontal Metallic Bob?

The angular momentum of a horizontal metallic bob affects its rotational motion, determining the speed and direction of its oscillations. As angular momentum is conserved, any changes in the bob's rotational motion must be accompanied by a corresponding change in its moment of inertia or angular velocity.

5. What are some real-world applications of Angular Momentum Horizontal Metallic Bob?

Some potential real-world applications of the Angular Momentum Horizontal Metallic Bob include using it to study the effects of gravity and air resistance on pendulum motion, or to demonstrate the principles of energy conversion and conservation in a simple and visual way.

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