Solve the Problem $1.6 \mathrm {~m} / \mathrm { sec } ^ { 2 }$

Multiple Choice

Solve the problem.
-On our moon, the acceleration of gravity is $1.6 \mathrm {~m} / \mathrm { sec } ^ { 2 }$ . If a rock is dropped into a crevasse, how fast will it be going just before it hits bottom 45 seconds later?

A) $3240 \mathrm {~m} / \mathrm { sec }$
B) $- 72 \mathrm {~m} / \mathrm { sec }$
C) $- 36 \mathrm {~m} / \mathrm { sec }$
D) $72 \mathrm {~m} / \mathrm { sec }$