Which describes a sound wave?

A)A sound wave travels in a vacuum.
B)A sound wave is a longitudinal wave.
C)A sound wave is an electromagnetic wave.
D)A sound wave has one constant speed.

The discovery that the universe appears to be expanding led to a widely accepted theory called a.) the big bang theory b.) the doppler effect c.) hubble’s law d.) solar nebular theory e.) the seyfert theory

When a bicycle coasts uphill, it moves slower and slower as it climbs. why? a. its kinetic energy is transforming into heat energy. b. its potential energy is transforming into kinetic energy. c. its kinetic energy is transforming into potential energy and heat energy. d. its potential energy is transforming into kinetic energy and heat energy.

What is friction? how does it affect the motion of an object?