# Acceleration due to gravity hw problem

I'm having difficulty with these two problems:

1. A mass is moving towards a massive crater (along the +x direction) on the Moon with an initial velocity of 636.8 cm/s. How far will the object fall in the first 1.1 seconds.

2. An object initially displaced 56.8 m (along the horizontal x direction) has in initial velocity downward (along the -y direction) of 152.4 cm/s. If this object is on Neptune, how far (in meters) will it fall after 22.5 seconds?

I'm not looking for the answers, I just need someone to point me in the right direction. I have attempted solving several different ways to no avail. The acceleration due to gravity on the Moon is 1.6 m/s2 and 14.07 m/s2 on Neptune. Thanks in advance!

JB Gibson

Staff Emeritus
Could you solve the problem if this was the Earth and not the moon or Neptune?

If not, it would help if you were to show us the several different ways you attempted.

I'm not able to visualize the concept right now. I realize the problems are dealing with 2-dimensional application, but I'm puzzled. I tried applied the formulas:

y=yo+vot+1/2gt^2
y=1/2gt^2
y=(vo sin)t-1/2gt^2

Let's see....my initial velocity in the y-position is 0 and I don't have any initial position. Like I mentioned, I just need someone to point me in the right direction. It's been a while since I had a Physics class. TIA!

JB Gibson

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If a=-g=-1.6m/s^2 on the moon, is the solution to problem #1:

y=-1/2gt^2=-96.8cm?

I submitted this as my answer, but it is incorrect. I don't know anymore; maybe I should just give up.

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Any help is greatly appreciated.