A ball of mass 1.2 kg is attached to a thin, uniform, rod of mass 2.40 kg and length 50.0 cm. The rod-mass system is free to rotate in a vertical plane without friction about a horizontal axis through the rod’s other end P. At a moment when the rod is vertical and moving to the left with the angular speed 2.5 rad/s, a wad of clay of mass 500 g, thrown with a velocity of 160 cm/s to the right, strikes perpendicularly 10 cm from the lower edge of the rod and sticks there. What is the angular momentum of the rod-mass system about the axis through P at the instant the rod is vertical and moving to the left with the angular speed 2.5 rad/s before the impact of clay? Give the magnitude and direction. What is the angular momentum of the clay about the axis
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.
A ball of mass 1.2 kg is attached to a thin, uniform, rod of mass 2.40 kg and length 50.0 cm. The rod-mass system is free to rotate in a vertical plane without friction about a horizontal axis through the rod’s other end P. At a moment when the rod is vertical and moving to the left with the angular speed 2.5 rad/s, a wad of clay of mass 500 g, thrown with a velocity of 160 cm/s to the right, strikes perpendicularly 10 cm from the lower edge of the rod and sticks there.
- What is the
angular momentum of the rod-mass system about the axis through P at the instant the rod is vertical and moving to the left with the angular speed 2.5 rad/s before the impact of clay? Give the magnitude and direction. - What is the angular momentum of the clay about the axis through P before hitting the rod? Give magnitude and direction.
- Calculate its
angular velocity (magnitude and direction) of the system immediately after the impact of the clay.
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