A stone is thrown vertically up from the ground with a velocity of 90 m/sec. How long must one wait before dropping a second stone from the top of a tower 180 m. high if the two stones are to pass each other 60 m. from the top of the tower?

Plss anybody know how to do this? ? i need the answers from a through d

The rocket is fired vertically and tracked by the radar station shown. when θ reaches 66°, other corresponding measurements give the values r = 32700 ft, r¨ = 85 ft/sec2, and θ˙ = 0.019 rad/sec. calculate the magnitudes of the velocity and acceleration of the rocket at this position.

The frequency of the fundamental of the guitar string is 320 hz. at what speed v do waves move along that string?