Ke = (1/2) m v^2 = (1/2) m (21^2)
gain of potential energy during rise
= m g h = m (9.81)(15.8)
so
Ke at 15.8 = (1/2) m v^2 = (1/2)m(21^2) - m (9.81)(15.8)
m cancels, so compute v at 15.8
v= Vi - g t
so
0.81 t = 21 - v
A stone is thrown vertically upward with a speed of 21.0 m/s
a)How fast is it moving when it reaches a height of 15.8 m
b)How much time is required to reach this height?
1 answer