Question

A car goes from rest to 30 m/s in 12 s with constant acceleration. How long does it take the car to go from rest to 15 m/s with the same acceleration?

Answer 1

Answer:

6 s

Explanation:

First of all, we calculate the acceleration of the car in the initial situation, using the equation

$a=\frac{v-u}{t}$

where

v = 30 is the final velocity of the car

u = 0 is the initial velocity

t = 12 s is the time taken

Substituting,

$a=\frac{30-0}{12}=2.5 m/s^2$

So, this is the acceleration of the car.

In the second situation, the car velocity goes from

u = 0

to

v = 15 m/s

So, we can use again the same equation to find t, the time it takes for the velocity of the car to change between these values:

$t=\frac{v-u}{a}=\frac{15-0}{2.5}=6 s$