On the moon, acceleration resulting from gravity, g, is about 5.3 ft/s2. which expression gives the time, in seconds, it would take a dropped penny to fall 100 ft on the moon?

, 6.1 s

Explanation:

The motion of the dropped penny is a uniformly accelerated motion, with constant acceleration

towards the ground. If the penny is dropped from a height of

the vertical position of the penny at time t is given by the equation

where the negative sign is due to the fact that the direction of the acceleration is downward.

We want to know the time t at which the penny reaches the ground, which means h(t)=0. Substituting into the equation, it becomes

And re-arranging it, we find an expression for the time t:

And substituting the numbers, we can also find the numerical value:

d is the correct answer