Question

Acceleration: A driver is traveling eastward on

adirt road when she spots a pothole ahead. She slows her car from
14m/s to 5.5 m/s in 6.0s. What is the car's acceleration?

Answer 1

`-1.42 m/s^2` is the car's acceleration.

Step-by-step explanation:

Initial velocity of the driver = u = 14 m/s

Final velocity of the driver = v = 5.5 m/s

Duration of time in which 14 m/s velocity is changed to 5.5 m/s = t = 6.0 s

Acceleration of the driver = a

Using first equation of motion: v = u + at

`5.5 m/s=14 m/s+a* (6.0 s)`

`5.5 m/s-14m/s =a* 6.0 s`

`-8.5 m/s=a* 6.0 s`

`a=(-8.5 m/s)/(6.0 s)=-1.417 m/s^2\approx -1.42 m/s^2`

Negative sign indicates the that is deceleration is occurring that is speed of the car is decreasing.