A car is traveling at 20.8 m/s when the driver sees a dog run out into the street. From the time the driver applies the brakes, it takes 3.58 s for the car to come to a stop. What is the average acceleration during that period?
the velocity changes by -20.8 m/s in 3.58s, for an acceleration of
(-20.8 m/s) / 3.58s = -5.8 m/s^2
To find the average acceleration, we need to first find the change in velocity of the car during the given time period.
The initial velocity of the car is 20.8 m/s, and the final velocity is 0 m/s because the car comes to a stop. Therefore, the change in velocity is:
Change in velocity = Final velocity - Initial velocity
Change in velocity = 0 m/s - 20.8 m/s
Change in velocity = -20.8 m/s
Since the change in velocity is negative, it means that the car is decelerating (slowing down) during this period.
The time taken for the car to come to a stop is 3.58 s.
Now, we can calculate the average acceleration using the formula:
Average acceleration = Change in velocity / Time taken
Plugging in the values:
Average acceleration = -20.8 m/s / 3.58 s
Calculating this, we find:
Average acceleration ≈ -5.81 m/s²
So, the average acceleration during that period is approximately -5.81 m/s² (meters per second squared). The negative sign indicates that the car is decelerating.