Question

What is the acceleration of a car that slows down from 60 m/s to 40 m/s during a period of 10 seconds

Answer 1

Answer:
`a=-2m/s^(2)`

Acceleration
`a` is the variation of Velocity
`\Delta V` in time
`\Delta t` :

`a=(\Delta V)/(\Delta t)` (1)

This can be written as:

`a=(V_(f)-V_(o))/(t_(f)-t_(o))` (2)

Where:

`V_(f)=40m/s` is the final velocity

`V_(o)=60m/s` is the initial velocity

`t_(f)=10s` is the final time

`V_(o)=0` is the initial time

`a=(40m/s-60m/s)/(10s-0)`

`a=(-20m/s)/(10s)`

Finally:

`a=-2m/s^(2)`

The negative sign means the car is desaccelerating