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Rotational Motion and Inertia

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If the angular momentum of a rotating body is increased by 200%, then its kinetic energy of rotation will be increased by

800%

A ring, a solid sphere, and a thin disc of different masses rotate with the same kinetic energy. Equal torques are applied to stop them. Which will make the least number of rotations before coming to rest?

All will make the same number of rotations

The angular velocity of a body is ω = 2ˆi + 3ˆj + 4kˆ and a torque τ = ˆi + 2ˆj + 3kˆ acts on it. The rotational power will be

20 W

A flywheel of moment of inertia 0.32 kg-m² is rotated steadily at 120 rad/sec by a 50 W electric motor. The kinetic energy of the flywheel is

<p>2304 J</p> Signup and view all the answers

If the torque acting on a rotating body is doubled, its rotational power will be increased by

<p>400%</p> Signup and view all the answers

What happens to a person's moment of inertia when they stretch out their limbs?

<p>It increases</p> Signup and view all the answers

What is the difference between translation and rotation?

<p>Translation is motion along a straight line, rotation is motion around a fixed axis</p> Signup and view all the answers

What is a characteristic of a rigid body?

<p>It can rotate with all parts locked together</p> Signup and view all the answers

What is the purpose of internal forces in a system?

<p>To enable the particles to form a well-defined system</p> Signup and view all the answers

What is the main topic of study in this chapter?

<p>Rotatory motion of a rigid body about a fixed axis</p> Signup and view all the answers

What is the moment of inertia of a ring of radius 0.5 m and mass 10 kg?

<p>2.5 kg m^2</p> Signup and view all the answers

What is the rotational kinetic energy of a rotating body?

<p>1/2 Iω^2</p> Signup and view all the answers

What is the torque of an automobile engine that develops 100 kW when rotating at a speed of 1800 rev/min?

<p>531 N-m</p> Signup and view all the answers

What is the ratio of rotational kinetic energy to translational kinetic energy for a solid cylinder?

<p>2/5</p> Signup and view all the answers

What is the angular velocity of a ring rotating about its diameter with an angular velocity of 20 rad/s?

<p>20 rad/s</p> Signup and view all the answers

What is the effect on the moment of inertia of a diver when he stretches out his limbs in mid-air?

<p>It increases</p> Signup and view all the answers

What is the characteristic of a rigid body?

<p>It can rotate with all parts locked together</p> Signup and view all the answers

What is the difference between translation and rotation?

<p>Translation is motion in a straight line, rotation is motion in a circle</p> Signup and view all the answers

Why does the diver's motion change from a high angular speed to a gentle speed when he enters the water?

<p>Because of the change in his moment of inertia</p> Signup and view all the answers

What is the purpose of internal forces in a system?

<p>To enable the particles to form a well-defined system</p> Signup and view all the answers

A cylindrical shell of radius 0.2 m and mass 5 kg is rotating about its axis with an angular velocity of 15 rad/s. What is its rotational kinetic energy?

<p>225 J</p> Signup and view all the answers

A solid sphere of radius 0.4 m and mass 10 kg is rotating about an axis passing through its center with an angular velocity of 20 rad/s. What is its moment of inertia?

<p>0.48 kg-m²</p> Signup and view all the answers

A ring of radius 0.3 m and mass 8 kg is rotating about its diameter with an angular velocity of 15 rad/s. What is its angular momentum?

<p>30 kg-m²/s</p> Signup and view all the answers

A compound pendulum consists of a rod of length 0.5 m and mass 2 kg, and a point mass of 1 kg attached to its end. What is its moment of inertia about an axis passing through the pivot?

<p>0.500 kg-m²</p> Signup and view all the answers

A disc of radius 0.2 m and mass 5 kg is oscillating about an axis passing through its center with a frequency of 2 Hz. What is its rotational kinetic energy?

<p>12.56 J</p> Signup and view all the answers

If the moment of inertia of a rotating body is increased by 50%_about a particular axis, then its angular velocity about that axis will be increased by

<p>25%</p> Signup and view all the answers

A solid sphere and a thin disc of different masses rotate with the same angular velocity. If the torque acting on them is the same, which will have the higher rotational kinetic energy?

<p>The solid sphere</p> Signup and view all the answers

A compound pendulum consists of two point masses connected by a light rod of length 1m. If the moment of inertia of the pendulum about the pivot is 0.5 kg-m², what is the angular frequency of the pendulum?

<p>1.41 rad/s</p> Signup and view all the answers

A rotating body oscillates about a stable equilibrium position. If the amplitude of the oscillations is 0.1 rad, what is the maximum angular velocity of the body?

<p>0.5 rad/s</p> Signup and view all the answers

If the rotational kinetic energy of a rotating body is increased by 400%, then its angular velocity will be increased by

<p>200%</p> Signup and view all the answers

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