When a rigid body rotates about a fixed axis, every particle in the body moves in a circular path. As shown in the figure below, the arclength As between the angular positions 0, and 0, is given as As = rA8. Do you agree with this equation? rotational motion (a) In the limit where Að is very small, then As can be consider as a straight line. Is this true or false? (b) It follows from statement (a) that any points along the circular path there is a tangential velocity (v) that is always perpendicular to the radius of the rotating body. Hence, if we divide both sides of the equation As = rÃo by At, justify that we will get vy = rw. This result indicates that the direction of the particle's velocity is tangential to its circular path at each point. Most importantly, for example, this result tells us the relation- ship between the angular velocity of the wheel of the car and linear velocity of the car. Reference line - A0 At (e) If the angular velocity changes by A, then the rotating object's linear speed will change by Arg. Hence, we will have An = rAw. Is this a true statement? (d) If this changes takes place in some smallAt and if we divide both sides of the equation Ar = rAw by At, justify that we will get ae = ra, where az is called the tangential acceleration and a is the rigid body angular acceleration. Most importantly, for example, this result tells us the relationship between the angular acceleration of the wheel of the car and the linear acceleration of the car.
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.
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