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## Homework Statement

There are two cars and the situation is located at a crossroad. car 1 is travelling south and car 2 is travelling east. For some strange reason car 2 has slammed the brakes and stopped right in the middle of the intersection, causing car 1 to 't-bone' crash into car 2. the mass of the cars are given:

mass(car1) = 1875 kg

mass(car2) = 1051 kg

the distance of car1's skid marks are = 16m

The speed limit on the crossroad is 50 km/h, the question of this problem is, was the driver of car1 speeding?

## Homework Equations

s = ut + 1/2at^2

F(friction) = [tex]\mu[/tex]mg

f=ma

P=mv ?

## The Attempt at a Solution

i think what the question is asking for is 'u', the speed car 1 was doing before he applied the brakes.

Therefore i used s = ut + 1/2at^2

however i am not given acceleration or time, 's' is the displacement of when car1 applied the brakes to when he hit car2, therefore 's' is the distance of the skidmarks ( assuming the car make skidmarks as soon as the driver applied the brakes :P) s = 16m

Using the Friction equation, F(friction) = [tex]\mu[/tex]mg i found the acceleration

F = [tex]\mu[/tex]mg

ma = [tex]\mu[/tex]mg

a = [tex]\mu[/tex]g

a = 0.8 x 9.8

= 7.84 m s-2

so all i need to do now is find the time of the braking , but i have tried everything and i cannot find anyway of doing it......i feel like im at a dead end, what should i do?