Which of the following word pairs correctly completes the sentence below? Lightning forms when charges drop to the lower parts of a cloud and charges build up on the ground below.

Which is not a source of noise pollution? a)airplanes b)acid rain c)machines d)cars

Imagine that someone pushes one marble toward a motionless marble. would there still be action-reaction forces involved in the collision? how might the marbles’ motions be changed? ?

Diamond will scratch quartz. true or false