1. ## physics homework

An experimental rocket car starting from rest reaches a speed of 560 km/h after a straight 400-m run on a level salt flat. Assuming that acceleration is constant, (a) what was the time of the run, and (b) what is the magnitude of the acceleration?

2. Originally Posted by twistedmexican
An experimental rocket car starting from rest reaches a speed of 560 km/h after a straight 400-m run on a level salt flat. Assuming that acceleration is constant, (a) what was the time of the run, and (b) what is the magnitude of the acceleration?
Let's do b) first.

$v^2 = u^2 + 2as$

$v = 155,5 m s^{-1}$

$24197,5 = 0 + 2a(400)$

$a = 30 m s^{-1}$

Now a)

$v = u + at$
$155,5 = 0 + (30)t$
$t = 5,18$