3. A bus is moving at 25 m/s when the driver steps on the brakes and brings the bus to a stop in 3.0 seconds. What is the average acceleration of the bus while braking?

-8.3 m/s²

Explanation:

The acceleration of an object is defined as the change in velocity over the change in time.

We are given the velocity of the bus, 25 m/s, and the time it takes the bus to stop, 3.0 s.

We know that if the bus stops, its velocity must be 0 m/s. Therefore, we can use these numbers to substitute into the acceleration formula.

The magnitude of the average acceleration of the bus while braking is 8.3 m/s².

However, in order for the bus to slow down and stop, the acceleration must have the opposite sign of the velocity.

This means that the acceleration is negative whilst the velocity is positive. So, the average acceleration of the bus while braking is -8.3 m/s².