Working out the speed a parked car travels after a moving car hits it

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In summary, The problem involves calculating the speed of a parked car after it is hit by another car. The mass and speed of both cars before and after the collision are given, and the conservation of momentum principle is applied. The resulting momentum of Car A is then divided by its mass to determine its speed.
  • #1
reefcake
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Hi I'm forensics student and I'm having trouble with this problem as i don't know how to solve it I would really like to to know the method.

Homework Statement


Calculate the speed in ms-1 at which a parked 1840kg "car A" will be traveling once "car B" crashes into it. assuming that "car B" continues to move forward at 8.4ms-1 after the crash.

info on Car A: Mass(m)= 1840kg, Speed(v)=0 ms-1

info on Car B: Mass(m)= 1400kg, Speed(v)= 26.82 ms-1 Momentum(p), 37548 kg-ms-1
ending speed= 8.4ms-1, Ending momentum= 11760 kg-ms-1

Homework Equations


p=mv (conservation momentum)
F=ma (Newtons 2nd law of motion)
A= uv/t (working out acceleration)



Thanks

reefcake
 
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Welcome to PH.

After the collision, what momentum will Car A have if momentum is really conserved?
 
  • #3
SammyS said:
Welcome to PH.

After the collision, what momentum will Car A have if momentum is really conserved?

Hi again ;)

yes that is problem as I'm not sure to go about working out as Car B transfers (p)25788kg-ms to car a but Car A is 1840kg, 440 kg heavier. do i divide (p)25788kg-ms (which is the transferred momentum) by 1840kg to get the speed of CarA?

thanks
 
Last edited:

1. How do you calculate the speed of a parked car after a moving car hits it?

To calculate the speed of the parked car after the collision, you will need to use the formula: Final Velocity = Initial Velocity + (Acceleration * Time). In this case, the initial velocity of the parked car is 0 m/s, and the acceleration is caused by the impact of the moving car. You will need to measure the time it takes for the parked car to come to a complete stop after the collision. Once you have these values, you can plug them into the formula to calculate the final velocity of the parked car.

2. What factors can affect the accuracy of the calculated speed?

There are several factors that can affect the accuracy of the calculated speed, including human error in timing the stop of the parked car, environmental factors such as the surface the cars are on, and the condition of the cars themselves. It is important to take multiple measurements and consider these factors to ensure the most accurate calculation.

3. Can the speed of the moving car be determined from this calculation?

No, this calculation only determines the speed of the parked car after the collision. To determine the speed of the moving car, you would need to use other methods such as measuring skid marks or analyzing the damage to both cars.

4. How can this calculation be used in a real-life scenario?

This calculation can be used in a real-life scenario to determine the speed of a car involved in a collision, which can be useful in accident investigations and determining liability. It can also be used in engineering and safety research to analyze the impact of car collisions.

5. Are there any limitations to this calculation?

Yes, there are limitations to this calculation. It assumes that the parked car was stationary before the collision and that the acceleration caused by the collision is constant. It also does not take into account other factors that may have affected the movement of the parked car, such as the angle of the impact or the weight of the cars involved.

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