Finding uniformly increasing acceleration.

[AcousticBruce]

Homework Statement

What is the acceleration of a rocket that travels uniformly from rest and travels 650m in the first 12 seconds.

Homework Equations

$$s=v_it+\frac{1}{2}at^2$$

$$a=\frac{\Delta v}{\Delta t}$$

The Attempt at a Solution

I pluged the acceleration equation into the first equation.

$$s=0(12)+\frac{1}{2}\frac{650}{12}12^2$$

that equaled 7800 m/s squared. That is so far off. The answer is 9 m/s squared.

 

[cepheid]

You don't need the second equation, and it's not useful because you don't know what the change in v was.

The first equation is perfectly adequate. You know s, you know v_i and you know t. Solve for a.