Question

A car slows from 22 m/s to 3.0 m/s at a constant rate after 110 meters. How many seconds are required before the car is traveling 3.0 m/s?

Answer 1

Recall that average velocity is given by

`v_(\rm ave)=(\Delta x)/(\Delta t)`

Under constant acceleration, we also have

`v_(\rm ave)=\frac{v_i+v_f}2`

Then

`(\Delta x)/(\Delta t)=\frac{v_i+v_f}2`

`\implies(110\,\mathrm m)/(\Delta t)=\frac{22(\rm m)/(\rm s)+3.0(\rm m)/(\rm s)}2`

`\implies\boxed{\Delta t=8.8\,\mathrm s}`