# Homework Help: Free fall help!

1. Oct 19, 2009

### inedhelpinphy

1. The problem statement, all variables and given/known data
a robot probe drops a camara off the rim of a 239 m high cliff on mars, where the freefall acceleration is -3.7 m/s^2. a. fiind the velocity wl wich the camara hits the ground. b. find the tiime required for it to hit the ground.

2. Relevant equations

3. The attempt at a solution

a=-3.7m/s^2
d=239m
vi=0m/s
vf=? ned to find
t=?

vf^2=-1786.6

2. Oct 19, 2009

### thaer_dude

d is actually -239m since it's falling. which means starting from 239 m and falling down to 0m so the change is -239m. the vf you will then calculate is actually negative like the acceleration since, again, it is falling downwards on the y axis

3. Oct 19, 2009

### tramar

Looks good except your displacement should be negative, $$\Delta d=0-239m$$

That will make your value for $$v_f^2$$ positive and you should be able to proceed.

4. Oct 19, 2009

### inedhelpinphy

tyvm!!! but i wanna just ask 1 more question... so then will the final velocity be negative?b/c it is falling

5. Oct 19, 2009

### thaer_dude

yes the vf will be negative, like i said in my previous reply >_>