Please help me, i don’t know the answer

Astone is dropped with no initial velocity from the top of a cliff and hits the ground a time of 3.9 s later. what is the height of the cliff, in units of meters? you may assume that air resistance is negligible. give the answer as a positive number question 15 a figure skater is rotating at a rate of 200 revolutions per minute. what is the angular speed, in units of rad/s? 200 o 20.9 12000 o 3.33

Which compound is held together by the electrostatic force between two ions? a. co2 b. cci4 c. h2s d. mgf2

The force needed to overcome static friction is usually less than that needed to overcome kinetic friction.true or false?