Question

A driver traveling at 30.0 m/s presses the brakes decelerates at -8.80 m/s^2. How much time, in second, does it take her to come to a full stop?

Answer 1

Answer:

It takes her 3.409 seconds to make a full stop.

Explanation:

The time it takes to make a full stop can be determined by the equation of velocity for a Uniformly Accelerated Rectilinear Motion:

$v_{f} = v_{i} + at$  (1)

Where $v_{f}$ is the final velocity, $v_{i}$ is the initial velocity, a is the acceleration and t is the time.

Equation (1) can be rewritten in terms of t:

$v_{f} - v_{i} = at$    

$t = \frac{v_{f} - v_{i}}{a}$  (2)  

For this particular case the final velocity will be equal to zero ($v_{f} = 0$):

$t = \frac{0 m/s - 30.0 m/s}{-8.80 m/s^{2}}$

$t = 3.409 s$

So it takes her 3.409 seconds to make a full stop.