true or false? anything that moves up and down or back and forth in a rhythmic way is vibrating.

Abearing is designed to a reduce friction b. support a load c.guide moving parts such as wheels, shafts and pivots d. all of the above

Avolcano erupts next to a grassland area in a valley. a. describe three ways in which material released by the volcano could impact the grassland area. b. describe three ways in which the grassland ecosystem could recover after a volcanic eruption.

The two stars in a certain binary star system move in circular orbits. the first star, alpha, has an orbital speed of 36 km/s. the second star, beta, has an orbital speed of 12 km/s. the orbital period is 137 d. a) what is the mass of the star alpha? b) what is the mass of the star beta?