Physics help?

Question

The tallest volcano in the solar system is the
31 km tall Martian volcano, Olympus Mons.
Assume: An astronaut drops a ball off the
rim of the crater and that the free fall acceler-
ation of the ball remains constant throughout
the ball's 31 km fall at a value of 2.9 m/s2.
(We assume that the crater is as deep as the
volcano is tall, which is not usually the case
in nature.)
a) Find the time for the ball to reach the
crater floor. Answer in units of s.


b) Find the magnitude of the velocity with
which the ball hits the crater floor. Answer in
units of m/s.

Answer 1

h=0.5gt^2
a) t=sqrt(2 h/g)
t=sqrt(2 x 31E+3/2.9)
t=146 s

b) V=gt=
V= 2.9 x 146=423 m/s