a rock at rest falls off a tall cliff and hits the valley below after 3.5s. What is the rock's velocity as it hits the ground?

Question

a rock at rest falls off a tall cliff and hits the valley below after 3.5s. What is the rock's velocity as it hits the groung.

 

Answer 1

Hi Bob;

v=(v_O)+at

v_O is original velocity.  It is zero.

v=at

Acceleration due to gravity 9.8 m/s².

v=gt

v=(9.8 m/s²)(3.5 s)

The unit of seconds to the exponential of 1 is in the denominator and numerator.  It cancels...

v=(9.8 m/s)(3.5)

The only units remaining are m/s.  This is what we want...

v=34.3 m/s