A boy is standing on a bridge over a creek which flows 35 ft below. He tosses a stone right up with a velocity of 12 feet per second. How high above the water

Question

A boy is standing on a bridge over a creek which flows 35 ft below. He tosses a stone right up with a velocity of 12 feet per second. How high above the water will the stone reach before it falls into the water? Use the vertical motion model:

h = –16t2 ± v0t + h0

Answer 1

h(t) = -16t² + 12t + 35

 

v(t) = at + v₀ = -gt + 12 = -32t + 12

 

Maximum height occurs when v(t) is instantaneously zero.

 

-32t + 12 = 0

 

t = 12/32 sec = 0.375 sec

 

Plug this t in h(t) to get h_max. 

 

By the way, the correct category for this question us KINEMATICS, not KINETICS.  The latter refers to rates of chemical reactions.