- #1

Stormblessed

- 24

- 2

## Homework Statement

Two cars are 1.4 km apart and driving towards each other. One car starts from rest and accelerates uniformly at 1.2 m/s^2. The other car is driving at a constant speed of 18 m/s. When will the cars meet?

## Homework Equations

d=vt

d=ut + 1/2at^2

d=vt-1/2at^2

v^2 = u^2 + 2ad

Note: u is initial velocity and v is final velocity

## The Attempt at a Solution

The answer provided by the teacher is 36 seconds. I don't know how to get there. I understand what to do if both cars have constant speed (create two equations equal to each other and solve for time) but I don't know what to do if one car is accelerating. If I use the algebraic method, I am getting 30 s instead of 36 s.

d1 = 1/2at^2

d1 = 1/2(1.2)t^2

d1 = 0.6t^2

d2 = vt

d2 = 18t

d1 = d2

0.6t^2 = 18 t

t = 30 s (which is incorrect)