A ball is thrown straight up with a speed of 3/frac{m}{s}, and it hits the ground with a speed of 15/frac{m}{s}. How tall is the tower? Ignore air resistance, and answer in meters.

Height of tower is 11 meters

Explanation:

We have equation of motion v² = u² + 2as

Initial velocity, u = 3 m/s upwards

Acceleration, a = - 9.81 m/s² downwards

Final velocity, v = - 15 m/s downwards

Substituting

v² = u² + 2as

(-15) ² = 3² + 2 x - 9.81 x s

s = - 11 m that is downward

Form the initial position it travels 11 meter downward.

Height of tower is 11 meters