1. ## Velocity

I know this seems so easy, but I can't figure this out.

The problem:

What is the velocity of an object dropped from a height of 130 m when it hits the ground?

I know that the formula for velocity is v(t)=v0-gt, but I can't figure out how to determine what some of those variables are. And I can't figure out how to incorporate the height, which I assume should be some form of s(t). Any help would be greatly appreciated!

2. Originally Posted by A5HLEY
I know this seems so easy, but I can't figure this out.

The problem:

What is the velocity of an object dropped from a height of 130 m when it hits the ground?

I know that the formula for velocity is v(t)=v0-gt, but I can't figure out how to determine what some of those variables are. And I can't figure out how to incorporate the height, which I assume should be some form of s(t). Any help would be greatly appreciated!
You need 2 equations here:

a = acceleration. It's $\displaystyle 9.81\ \frac m{s^2}$
d = distance: 130 m
t = time

You are dealing with an uniformly accelerated motion.

$\displaystyle d = \frac12 \cdot a \cdot t^2$

$\displaystyle v = a \cdot t$

$\displaystyle 130 = \frac12 \cdot 9.81 \cdot t^2 ~\implies~t\approx 5.148\ s$

$\displaystyle v = 9.81\ \frac m{s^2} \cdot 5.148\ s \approx 50.5 \ \frac ms$