Question

If a car traveling at \(28 \mathrm{m} / \mathrm{s}\) is brought to a full stop in \(4.0 \mathrm{s}\) after the brakes are applied, find the average acceleration during braking.

Short answer

Answer: The average acceleration during braking is -7 m/s².

Step-by-step solution

Identify the given values

The given values are: Initial velocity (vi) = 28 m/s Final velocity (vf) = 0 m/s (since the car comes to a full stop) Time taken (t) = 4.0 s

Write down the formula for average acceleration

The formula for average acceleration (a) is: a = (vf - vi) / t

Substitute the given values into the formula and solve

We plug in the given values into the formula: a = (0 - 28) / 4.0

Calculate the average acceleration

Performing the calculations: a = -28 / 4.0 a = -7 \mathrm{m/s^2}

Final Answer

The average acceleration during braking is -7 m/s². Note that the negative sign indicates that the car is decelerating, or slowing down.