Suppose an astronaut drops a feather from 1.4 m above the surface of the Moon. If the acceleration due to gravity on the Moon is 1.62 m/s2 downward, how long does it take the feather to hit the Moon's surface?

Answer 1

Ignore air resistance, which is justifiable in an insignificant atmosphere.

S=ut+(1/2)at²
u=initial velocity=0
a=acceleration du to gravity=-1.62 m/s/s
S=displacement = -1.4 m (downwards)
t=time in seconds

-1.4 = 0*t + (1/2)(-1.62)t²
t=sqrt(2*1.4/1.62)
=1.31 s.