Question

Ms. Stafford wants to try racing with a push start. A student pushes her at 5 m/s before the rocket kicks in. The rocket still only accelerates her at a rate of 4 m/s/s. Calculate how many meters she travels in 7 seconds after the rocket kicks in.

Answer 1

The initial velocity of Ms. Stafford is $v_0 = 5 m/s$, while her acceleration is 
$a=4 m/s^2$
This is a uniform accelerated motion, so we can calculate the total distance travelled by Ms. Stafford in a time of $t=7.0 s$ using the law of motion for a uniform accelerated motion:
$S=v_0t + \frac{1}{2} at^2 = (5 m/s)(7.0 s)+ \frac{1}{2}(2 m/s^2)(7.0 s)^2 = 84 m$