Question

a car has an initial velocity of 55 m/s. when brakes are applied, it accelerates at a constant rate and stops in 7.2 s. what is the acceleration of the car? (1 point)
-7.6 $\frac{m}{s^{2}}$
-396 $\frac{m}{s^{2}}$
-55 $\frac{m}{s^{2}}$
-0.13 $\frac{m}{s^{2}}$

Explanation:

Step1: Identify the formula

The formula for acceleration is $a=\frac{v - u}{t}$, where $v$ is final - velocity, $u$ is initial - velocity, and $t$ is time.

Step2: Determine the values of variables

The initial velocity $u = 55\ m/s$, the final velocity $v = 0\ m/s$ (since the car stops), and the time $t=7.2\ s$.

Step3: Substitute values into the formula

$a=\frac{0 - 55}{7.2}=\frac{- 55}{7.2}\approx - 7.6\ m/s^{2}$

Answer:

$-7.6\frac{m}{s^{2}}$