A rock is thrown downward from the top of a cliff with an initial speed of 20 m/s. If the rock hits the ground after 5.0 s, what is the height of the cliff? (Disregard air resistance. a =-g=-9.81 m/s2.)​ （i want step by step)

Which quantities are scalars? choose all that apply a.distance b.speed c. acceleration d.velocity

Point charges q1 = 51 µc and q2 = −27 µc are placed 1.0 m apart, with q2 on the right. what is the force (in n) on a third charge q3 = 19 µc placed midway between q1 and q2? (assume the positive direction is to the right. indicate the direction with the sign of your answer.)

Most of the volume of an atom is occupied by the