A20.0-kg rock is dropped and hits the ground at a speed of 90.0 m/s. calculate the rock’s gravitational potential energy before it was dropped. (ignore the effects of friction.)

Objects a and b are visible in the night sky. six months later they are still visible, but object b shows less parallax than object a. which object is closer? a. a b. b c. you would need to wait another six months in order to figure this out. d. you would need to know the objects' angular diameters in order to figure this out.