# UBER EASY QUESTION: just need to make sure.

1. May 20, 2010

### pfssassin

1. The problem statement, all variables and given/known data

Create a lab to find the gradational constant of the earth.

2. Relevant equations

a = d/(t^2)

3. The attempt at a solution

Just a general question. If you drop a object (air resistance negligible) and you know the t initial is 0 and you know the t final is w/e you get on your stop watch. You do d/t to get average velocity of the fallen object.

Now that you have the avrg velocity you know the V initial is zero and the speed rises to the avrg velocity, can you assume that a = V avrg / t?

Im in IB physics HL but just cant get my head around this one for some reason....

2. May 20, 2010

### Mindscrape

Okay, well if you are in IB physics HL you know calculus. Did you learn the mean value theorem?

$$v'(c)=a(c)=\frac{v(t_1)-v(t_0)}{t_1-t_0}$$

This will give you the mean acceleration. We know that gravity is constant, so it doesn't even matter that we get the mean, so you're good.

Why don't you just use the kinematic equation for height?

$$s(x)-s_0=v_0 t + .5 a t^2$$

3. May 20, 2010

### pfssassin

Thanks. Got it. I did think about the mean value theorem but we did not have a v initial and v final but just a v avrg. In the midst of all these upscale formulas I forgot the basic $$s(x)-s_0=v_0 t + .5 a t^2$$; Well I can argue that I didnt do mechanics since last year but thanks a lot.