To solve this problem, we can use the formula for acceleration:

$a = \frac{{v - u}}{{t}}$

where:

• $v$ is the final velocity,
• $u$ is the initial velocity,
• $t$ is the time taken.

In this problem:

• The car starts from rest, so $u = 0 \, \text{m/s}$.
• The final velocity $v = 40 \, \text{m/s}$.
• The time $t = 5 \, \text{s}$.

Substituting these values:

$a = \frac{{40 \, \text{m/s} - 0 \, \text{m/s}}}{{5 \, \text{s}}} = \frac{40}{5} = 8 \, \text{m/s}^2$

Therefore, the car's acceleration is $\mathbf{8 \, \text{m/s}^2}$, which corresponds to option B.

Would you like more details or have any questions?

Here are some related questions for practice:

1. If the car reached a speed of 60 m/s in the same time, what would the acceleration be?
2. How much distance would the car cover in the 5 seconds at this acceleration?
3. What would be the final velocity if the car accelerated at 8 m/s² for 10 seconds?
4. How long would it take for the car to reach 100 m/s with the same acceleration?
5. If another car accelerated to the same final speed in 10 seconds, what would be its acceleration?

Tip: Remember that when a problem involves "starting from rest," the initial velocity is zero, simplifying the acceleration calculation.