Question

A drag racer starts her car from rest and accelerates at 14 meters per second per second for the entire distance of 424 meters. how long does her race take

Answer 1

You can use this 'suvat' equation of linear motion

$s = ut + \frac{1}{2} a {t}^{2}$
From the question, the racer starts from rest so the initial velocity
$u = 0 {ms}^{ - 1}$

The acceleration,

$a= 14 {ms}^{ - 2}$

And distance
$s = 424m$

We can substitute this values to find t

$424= (0)t + \frac{1}{2} (14) {t}^{2}$

$424= 7{t}^{2}$

Dividing by 7, we have

$\frac{424}{7} = {t}^{2}$

$\sqrt{ \frac{424}{7} } = t$

$t = 7.8 \: s$

Therefore the race took 7.8 seconds