Question

A shuttle bus slows down with an average acceleration of -2.4 m/s2. How long does it

Answer 1

Answer:

$\boxed {\boxed {\sf 3.75 \ seconds }}$

Explanation:

Average acceleration is found by dividing the change in acceleration by the time.

$a=\frac{ v_f-v_i}{t}$

The shuttle bus has an acceleration of -2.4 meters per square second. It slows from 9.0 meters per second to rest, or 0 meters per second. Therefore:

$a= -2.4 \ m/s^2 \\v_f= 0 \ m/s \\v_i= 9 \ m/s$

Substitute the values into the formula.

$-2.4 \ m/s^2=\frac{0 \ m/s - 9 \ m/s}{t }$

Solve the numerator.

$-2.4 \ m/s^2 = \frac{-9 \ m/s}{t}$

We want to solve for t, the time. We have to isolate the variable. Let's cross multiply.

$\frac{-2.4 \ m/s^2}{1} = \frac{-9 \ m/s}{t}$

$-9 \ m/s *1= -2.4 \ m/s^2 *t$

$-9 \ m/s=-2.4 m/s^2*t$

t is being multiplied by -2.4. The inverse of multiplication is division, so divide both sides by -2.4

$\frac{-9 \ m/s }{-2.4 \ m/s^2} =\frac{ -2.4 \ m/s^2*t}{-2.4 \ m/s^2}$

$\frac{-9 \ m/s }{-2.4 \ m/s^2} =t$

$3.75 \ s=t$

It takes 3.75 seconds.