Question

A car starts from rest and accelerates uniformly for a five seconds along a straight road. If speed obtained by the car is 72 km/h, then its displacement is

Answer 1

50 meters

Step-by-step explanation:

Let's start by converting to m/s. There are 3600 seconds in an hour and 1000 meters in a kilometer, meaning that 72km/h is 20m/s.

`v_f=v_o+at`

Since the car starts at rest, you can write the following equation:

`20=0+a(5) \\\\a=20/ 5=4 m/s^2`

Now that you have the acceleration, you can do this:

`d=v_o+(1)/(2)at^2`

Once again, there is no initial velocity:

`d=(1)/(2)(4)(5)^2=2 \cdot 25=50m`

Hope this helps!