Question

a ball is thrown horizontally with an initial speed of 10ms from an 80 m cliff.how long does it take to reach the ground?

Answer 1

Given:

$h=80\:\rm m$

$g=9.8\:\rm m/s^2$

$v_0=10\:\rm m/s$

The time of motion is equal to the time of free falling:

$$t=\sqrt{\frac{2h}{g}}=\sqrt{\frac{2*80}{9.8}}=4.0\:\rm s$$