Question

If a car slows from 42 m/s to 37 m/s in a period of 6.0 s, what was the average acceleration?
Group of answer choices

-0.8 m/s2

-5.0 m/s2

-6.0 m/s2

5.0 m/s2

Answer 1

To calculate the average acceleration, we can use the formula:

\[
a = \frac{\Delta v}{\Delta t}
\]

where:
- \( a \) is the average acceleration,
- \( \Delta v \) is the change in velocity,
- \( \Delta t \) is the change in time.

Given:
- Initial velocity (\( v_i \)) = 42 m/s
- Final velocity (\( v_f \)) = 37 m/s
- Time interval (\( \Delta t \)) = 6.0 s

First, we calculate the change in velocity (\( \Delta v \)):

\[
\Delta v = v_f - v_i = 37 \, \text{m/s} - 42 \, \text{m/s} = -5 \, \text{m/s}
\]

Now we can plug this value into the acceleration formula:

\[
a = \frac{\Delta v}{\Delta t} = \frac{-5 \, \text{m/s}}{6.0 \, \text{s}} \approx -0.833 \, \text{m/s}^2
\]

Rounding to one decimal place gives:

\[
a \approx -0.8 \, \text{m/s}^2
\]

Thus, the average acceleration is **-0.8 m/s²**.

The correct answer is:
-0.8 m/s²