- #1

- 12

- 0

## Homework Statement

Pete got into into a car accident and collided with another vehicle, which resulted in the death of the second vehicles passenger, David. Whether Pete was speeding or not determines if he goes to jail. The speed limit where he got into the accident was 45mph. How fast was pete going at the point of collision and will he go to jail?

Given Data :

Mass of David’s Car(m2)

1115lbs

Mass of Pete’s car (m1)

1755lbs

Distance the cars skidded

13m

Final velocity post skid

0mph

Time of skid

22sec

Initial velocity of David’s car

47mph

Speed limit

45mph

## Homework Equations

$$ (m1v1) + (m2v2) = (m1 + m2)Vf $$

## The Attempt at a Solution

First I converted from lbs and mph to kg and m/s for the masses and velocity since we use kg and m/s in my class, I dont know if this was neccesary.

1151 lbs = 505.8 kg

1755 lbs = 796.1 kg

47mph = 21.01 m/s

Then I used my equation

$$ (m1v1) + (m2v2) = (m1 + m2)Vf $$

$$ (796.1*v1) + (505.8*21.01) = (796.1 + 505.8)0 $$

$$ (796.1*v1) + (10626.858) = 0 $$

$$ 796.1*v1/796 = -10626.8/796 $$

$$ v1 = 13.35 m/s $$

I then converted that from m/s to mph and got 29.86mph, which would mean he would not be speeding and not go to jail.

Although I got all the way through, i feel im wrong since they gave me the data for time and distance and i never even used them, which makes me feel like im forgetting something. Could someone help me out or check it to see if i did skip a step?