Angular Momentum
The momentum of an object is given by multiplying its mass and velocity. Momentum is a property of any object that moves with mass. The only difference between angular momentum and linear momentum is that angular momentum deals with moving or spinning objects. A moving particle's linear momentum can be thought of as a measure of its linear motion. The force is proportional to the rate of change of linear momentum. Angular momentum is always directly proportional to mass. In rotational motion, the concept of angular momentum is often used. Since it is a conserved quantity—the total angular momentum of a closed system remains constant—it is a significant quantity in physics. To understand the concept of angular momentum first we need to understand a rigid body and its movement, a position vector that is used to specify the position of particles in space. A rigid body possesses motion it may be linear or rotational. Rotational motion plays important role in angular momentum.
Moment of a Force
The idea of moments is an important concept in physics. It arises from the fact that distance often plays an important part in the interaction of, or in determining the impact of forces on bodies. Moments are often described by their order [first, second, or higher order] based on the power to which the distance has to be raised to understand the phenomenon. Of particular note are the second-order moment of mass (Moment of Inertia) and moments of force.
The wheel has radius ?? = 50 cm
and is free to rotate without friction about a
central axle. A force ?? = 15N is applied to
the wheel as shown, at distance ?? = 10 cm.
from the axle. ?? = 40°
What is the moment of inertia of the wheel?
What is the final
What is the direction of the torque vector?
Given: wheel radius = 50 cm
Force = 15N is applied to
Distance from the axle = 10 cm.
The wheel is free to rotate without friction about a central axle.
Moment of inertia: It is also known as the rotational inertia of the body. It is the opposition of the body which exhibits having the speed of rotation about its axis. It is measured as the product of the sum of the masses in the body with the square of the distance from the axis.
From definition the moment of inertia of the wheel is I = MR2
where M is the total mass and R is the radius of the wheel
I = 2500M
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