Question

A baseball is thrown straight downward with an initial speed of 40 ft=s from the top of the Washington Monu- ment (555 ft high). How long does it take to reach the ground, and with what speed does the baseball strike the ground?

Answer 1

Answer:

4.53 second, 195 ft/s

Explanation:

u = 50 ft/s

h = 555 ft

g = 32 ft/s^2

Let the time taken by the ball to reach the ground is t and the velocity of the ball as it hits the ground is v.

Use third equation of motion

$v^{2}=u^{2}+2as$

$v^{2} = 50^{2}+2\times 32 \times 555$

v = 195 ft /s

Thus, the ball strikes the ground with velocity 195 ft/s.

Use first equation of motion

v = u + at

195 = 50 + 32 t

32 t = 145

t = 4.53 second

Thus, the ball reach the ground in 4.53 second.