Question

1)    A stone is thrown downward from the edge of a building 19.6 m high with an initial velocity of 4.9 m/s. Determine:

a)    The velocity of the stone just before its strikes the ground

b)    The time the stone traveled downward

Answer 1

a) The velocity of the stone just before its strikes the ground is

$$v=\sqrt{v_0^2+2gh}=\sqrt{4.9^2+2·9.8·19.6}=20.2\text{ m/s}.$$

b) The time the stone traveled downward is

$$t=\frac{v-v_0}{g}=1.56\text{ s}.$$