Spot the false spinning statement

Exercise and reference answers

Questions

1. False statement

   The skater's angular momentum grows as she pulls her arms in.

   Statements

   1. A skater speeds up her spin by pulling her arms in.
   2. Her rotational kinetic energy rises as she pulls her arms in.
   3. The skater's angular momentum grows as she pulls her arms in.

2. False statement

   The Earth's angular momentum axis points at the Sun.

   Statements

   1. The Earth's angular momentum axis points at the Sun.
   2. Tidal friction is slowly slowing the spin of the Earth.
   3. The Earth precesses once in about 26,000 years.

3. False statement

   Angular acceleration is measured in radians per second.

   Statements

   1. Radians are dimensionless in any angle calculation.
   2. Angular acceleration is measured in radians per second.
   3. Tangential and centripetal acceleration are perpendicular.

4. False statement

   Kinetic energy also held steady in that same collision.

   Statements

   1. Angular momentum held steady in the disk and stick collision.
   2. The force acting at the nail exerted no torque there.
   3. Kinetic energy also held steady in that same collision.

Instructions

Tap the one claim in each set that is not true.

Explanation