Question

Alice is driving down the road at 86 m/s when she sees a speed limit sign for 7m/s. What is

the magnitude of her average acceleration if it takes her 8s to slow down?

Answer 1

`-9.875 m/s^(2)`

Step-by-step explanation:

Acceleration,
`a=\frac {v-u}{t}`

Where v and u are the final and initial velocities of Alice's car respectively, t is the time taken for Alice's car to attain velocity of 7 m/s.

Substituting 7 m/s for v, 86 m/s for u and 8 s for t then

`a=\frac {7-86}{8}=-9.875 m/s^(2)`

Therefore, the car decelerates at a rate of
`9.875 m/s^(2)`