# Homework Help: Finding Acceleration of Gravity of Fictional Planet

1. Oct 21, 2009

### to819

In preparation for my upcoming first exam I was doing all of the suggested problems throughout the chapters. Everything was fine until this problem:

1. The problem statement, all variables and given/known data
An astronaut on the planet Zircon tosses a rock horizontally with a speed of 6.95m/s. The rock falls through a vertical distance of 1.4m and lands a horizontal distance of 8.75m from the astronaut. What is the acceleration of gravity on Zircon?

2. Relevant equations
Distance=speed x time
Speed=distance/time

3. The attempt at a solution

8.75m/6.95m/s=1.26s

1.4m/1.26s=1.11m/s

Now, I thought this was correct but according to the back of the book the answer is 1.77m/s which would be 1.4*1.26. Am I misunderstanding something?

2. Oct 21, 2009

### Janus

Staff Emeritus
You found the speed of the rock if it fell at a constant speed. You are meant to find the acceleration of the rock. You need to use an equation that relates time, distance and acceleration.

3. Oct 21, 2009

### kellenm

Are you doing projectile motion?