Angular Momentum: Solving Homework Problem

In summary, a point particle slides across a frictionless, horizontal table at a speed of 4.1 m/s and strikes a motionless uniform rod at a distance of 0.11 m below its center of mass. The rod has a mass of 2.74 kg and a length of 0.934 m, and the block has a mass of 0.621 kg. Using conservation of angular momentum, the speed of the center of mass of the rod after the collision can be calculated, but the provided equations do not seem to give the correct solution.
  • #1
al86
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Homework Statement


A uniform thin rod (mass 2.74 kg, length 0.934 m) lies motionless on a frictionless, horizontal table. The rod is free to move in any direction on the table. A small block (a point particle of mass = 0.621 kg) slides across the table, moving at right angles to the rod, at speed 4.1 m/s. The block strikes the rod at a distance of 0.11 m below the center of mass, and stops. Assume the block does not stick to the rod

Homework Equations


vf, the speed of the center of mass of the rod after the collision


The Attempt at a Solution


I used the conservation of angular momentum:
mv=MV;
mvx=Iw: distance between the point of collison and the center of mass
then solve for V. But it does not seem to give me the right solution.
 
Last edited:
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  • #2
Your equations don't even have the correct dimensions.
 

What is angular momentum?

Angular momentum is a physical quantity that describes the rotational motion of an object. It is a vector quantity that depends on an object's mass, velocity, and distance from a fixed point.

How is angular momentum calculated?

Angular momentum is calculated by multiplying an object's moment of inertia (a measure of its rotational mass) by its angular velocity (the rate at which it rotates).

What is the law of conservation of angular momentum?

The law of conservation of angular momentum states that the total angular momentum of a system remains constant unless an external torque is applied. This means that in a closed system, the initial angular momentum will be equal to the final angular momentum.

How is angular momentum related to torque?

Torque is the rotational equivalent of force, and it is responsible for changing an object's angular momentum. The greater the torque applied, the faster the object will rotate and the greater its angular momentum will be.

How do you solve homework problems involving angular momentum?

To solve homework problems involving angular momentum, it is important to understand the concepts of angular momentum, torque, and the law of conservation of angular momentum. It is also helpful to draw diagrams and carefully label all variables before plugging them into the appropriate equations.

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