Can sound be produced in a vacuum? explain?

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

Use the ratio form of kepler’s third law, = , and the data provided to determine the time it takes mars to orbit the sun. round your answer to the nearest tenth. earth’s orbital period = 1.0 earth year earth’s distance from the sun = 1.0 au mars’s distance from the sun = 1.5 au it takes mars about ⇒ 1.8 earth years to orbit the sun.

Diego is trying to lift a piano to the second floor of his house. diego uses a pulley system and gives a big lift to the piano.the piano moves upward, then stops, and then it starts to fall to the ground. which list best describes the forces on the piano in the proper order? positive force → balanced force → negative force negative force → balanced force → positive force positive force → unbalanced force → negative force negative force → unbalanced force → positive force