Question

A car moving along straight road at 30m/s slows uniformly to a speed of 10m/s in a time of 5.0s. Determine

(a) acceleration of the car

(b) distance it moves during the third second

Answer 1

Given:

$v_1=30\:\rm m/s$

$v_2=10\:\rm m/s$

$\Delta t=5.0\:\rm s$

(a) the acceleration of the car

$$a=\frac{\Delta v}{\Delta t}=\frac{10-30}{5.0}=-4\:\rm m/s^2$$

(b) distance it moves during the third second

$$d(3)-d(2)=(30*3-4*3^2/2)\\ -(30*2-4*2^2/2)=20\:\rm m$$