*hurry its for a quiz* which of the following have angular momentum? choose all that apply. a. a stationary ferris wheel b. the wheels of a bike riding down the street c. the blades of a fan that is turned on d. a child sitting on a moving merry-go-round

The correct answers are :
B. The wheels of a bike riding down the street
C. The blades of a fan that is turned on
D. A child sitting on a moving merry-go-round

Let's see why. Keep in mind that the angular momentum is defined as

where m is the mass of the rotating object, v its velocity and r the radius of the circular trajectory.

A. stationary Ferris wheel --> this one has no angular momentum, because its velocity is zero (the wheel is stationary), so v=0 and the angular momentum is zero: L=0

B. The wheels of a bike riding down the street --> this one has angular momentum, because the edge of the wheel is moving with speed v

C. The blades of a fan that is turned on --> this one also has angular momentum, because the fan is moving as well

D. A child sitting on a moving merry-go-round --> also this one has angular momentum, which is given by 

where m is the child mass, v its velocity and r the radius of the merry-go-round.

The kinetic energy also decreases when the particles in a liquid state decrease. the liquid is solidifying so the energy is cooling down.