Rotational Inertia

What happens to her angular velocity when a figure skater brings in her arms? (angular momentum= moment of inertia X angular velocity)

• Increases her angular velocity

• Decreases her angular velocity

• Has no effect

Consider a wind turbine having moment of inertia 240,000 kg m². If a 120 kg person were holding on to the edge of the turbine 10 m from its center the torque due to the person is ________ and the angular acceleration of the turbine is ________.

• 120,000 Nm; 0.05 rad/s²

• 12,000 Nm; 0.005 rad/s²

• 240,000 Nm; 0.05 rad/s²

• 12,000 Nm; 20 rad/s²

Tags

NGSS.HS-PS2-1

Rotational mass is also known as

• moment of inertia

• center of mass

• angular acceleration

• torque

Rotational mass is dependent on a object's ordinary mass AND how that mass is distributed within the object.

• True

• False

When building soap box cars which race by coasting downhill it is better to have solid wheels rather than ones of equal mass with spokes because

• The solid wheels have a lower moment of inertia and therefore accelerate faster.

• The solid wheels are easier to paint.

• The solid wheels have a higher moment of inertia and therefore retain more rotational energy.

• The wheels with spokes lose too much energy by heating up the air.

Tags

NGSS.MS-ETS1-1

NGSS.MS-PS2-1

NGSS.MS-PS3-1

NGSS.MS-PS3-5

It is possible for two objects of equal mass to have different rotational masses because

• Rotational mass depends on total mass and mass distribution.

• The objects may be made out of different materials.

• Rotational mass is always half the total mass.

• An object not rotating has no rotational mass.

A solid sphere and a hollow sphere of the same mass and radius are released from the top of an inclined plane. Which one will reach the bottom first?

• A) The solid sphere

• B) The hollow sphere

• C) Both will reach at the same time

• D) It depends on the angle of inclination

Which of the following factors does NOT affect the rotational inertia of an object?

• A) Mass of the object

• B) Distribution of mass around the axis of rotation

• C) Shape of the object

• D) Color of the object

A disk and a ring, both with the same mass and radius, are rolling down a hill. Which one will reach the bottom first?

• A) The disk

• B) The ring

• C) Both will reach at the same time

• D) It depends on the surface of the hill

Tags

NGSS.HS-PS2-1