- #1

## Homework Statement

I apologize in advance because this is a long question.

This is a scenario based question where I role play as an intern for the Montreal Police Collision Investigation Unit. Basically I have to determine the initial velocity of vehicles to determine whether or not they are liable under Section 249 (3) of the Criminal Code, meaning if they are going over 30 km/hr over the limit, they face charges.

Now for the data:

- Debris was found at a distance of 12.63 m from the red vehicle. (I am sure that this is data thrown in to distract)
- Debris was also found 11.87 m from the yellow vehicle. (I am also sure that this is unneeded.)
- The yellow vehicle braked in a straight line.
- The red vehicle veered 6.5º from its initial course.
- The marks of the impact on the red vehicle show that it was heading 98º away from the yellow vehicle at the moment of collision.
- Prior the point of collision, there are skid marks over a distance of 30m.
- The speed limit is 70 km/hr.
- Mass of vehicle 1 (yellow) 2674 kg
- Mass of vehicle 2 (red) 1110 kg

Velocity indicators are defined as follows:

- V1IB: velocity of vehicle 1 before initial braking
- V1B : velocity of vehicle 1 just before impact
- V2B : velocity of vehicle 2 just before impact
- V1A: velocity of vehicle 1 just after impact
- V2A: velocity of vehicle 2 just after impact
- (this is for the attached visual of crash)

Mass of friction block: 9 kg

Ftension = 75.8 N

(I am suppose to be prosecuting the driver of this car and will be presenting my case to my teacher)

(I attached the visual that was given with the worksheet)

## Homework Equations

Fk=μk(Fn)

Fnet=ma

Vf^2 = V0^2 + 2ax

## The Attempt at a Solution

I have already figured out the coefficient of friction and acceleration using the above equations.

Coefficient of friction: .86

Acceleration: 8.428 m/s^2

I also found the velocity using 70 km/h as my initial and 30 m as x. I ended up getting 70.0036 km/h, which would mean the driver was not speeding but want to make sure that I have the correct math. My teacher also said that I must find the velocity of the car before and after the collision and I am not sure how to approach the problem further.