Which variable stars have pulsation periods between 1.5 hours and 1.2 days?

A. Cepheid variables

B. Protostars

C. RR Lyrae variables

D. Nebulas

What is the kinetic energy of an automobile with a mass of 1252 kg traveling at a speed of 12 m/s?

A battery with internal resistance r is connected to a load resistance R. If R is increased, does the terminal voltage of the battery increase, decrease, or stay the same?

A projectile is launched at 37 degrees to the horizontal with a speed of 200 m/s from position A. How many seconds elapse after launch of the projectile before it returns to its original elevation at C? a. 12 s b. 16 s c. 41 s d. 33 s e. 24 s

why does a simple oscillating pendullum not produce a vibrating sound

Consider two planets in space that gravitationally attract each other if the mass of one of them stays the same and the mass of the other is doubled AND the distance between them is doubled, then the force between them changes by what factor? A.

Imagine two artificial satellites orbiting earth at the same distance. one satellite has a greater mass then the other one which of the following would be true about there motion? 1.

What is energy? (Not the answer from google search.)

Explain why the friction force between two surfaces increases if the force is pushing the surfaces together increases.

As energy moves in waves through the water, the water moves a. in waves toward shore. c. in the direction of the waves. b. in a small circular movement. d. against the current.

Which of the following values represents an index of refraction of an actual material? A. 0 B. 1 / 4 C. 5 / 4 D. 1 / 2