Calculating Velocity of Wreckage After Collision

In summary, the conversation discusses a collision between two cars, one traveling east and the other traveling north, with one car having safety features that ensure the occupants come to rest relative to the car. The task is to calculate the velocity of the wreckage immediately after the collision using conservation of momentum and determine the change in momentum of both vehicles. The conversation also mentions converting units and using equations such as momentum and kinetic energy.
  • #1
Chica1975
63
0

Homework Statement


A car of mass 950kg traveling at 60km/h in an easterly direction collided perfectly inelastically with another care of mass 1250kg traveling at 55.0km/h in a northerly direction. The design of the smaller care incorporated safety features which ensured that any occupants came to rest relative to the care in a tie of 250m/s. Both vehicles had one occupant of 75.0kg

calculate the velocity of the wreckage immediately after the collision.

Use conservation of momentum to determine the change in momentum of both vehicles



Homework Equations


m1v1 + m2v2 = m'1v'1 + m'2 v'2
I am not sure if the kinetic energy equation fits here too?
.5 m1 v1 E2 + .5 m2 v2 E2 = .5 m1 v'1E2 + .5 m2v'2E2
r= square root (xE2 +yE2)
p=mv

The Attempt at a Solution



I converted all the km/h to m/s
I calculated the momentum of each vehicle p=mv (I also included the weight of the driver for each). Using the answers I found the resultant.
I then rearranged the equation to find v and got the right answer in it.

I am now really struggling with the conservation of momentum - these always get me out. I can't seem to use the right equation and am just blank.

Can someone let me know = thank you. :)
 
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  • #2
Hi Chica1975! :smile:
Chica1975 said:
I am now really struggling with the conservation of momentum - these always get me out. I can't seem to use the right equation and am just blank.

As I said in the other thread …
tiny-tim said:
You always need two equations to solve a collision question … one is always conservation of momentum, the other is either conservation of energy or some other constraint like "perfeclty inelastic" or " coefficient of restitution = 0.5".

In this case, your second equation (which you did use) is vf1 = vf2 …

you don't need, and mustn't use, conservation of energy! :wink:

(But you always need conservation of momentum)
 

FAQ: Calculating Velocity of Wreckage After Collision

1. How is the velocity of wreckage after a collision calculated?

The velocity of wreckage after a collision can be calculated using the formula v = (m1v1 + m2v2) / (m1 + m2), where m1 and v1 are the mass and velocity of the first object and m2 and v2 are the mass and velocity of the second object.

2. Is the velocity of wreckage affected by the mass of the objects involved in the collision?

Yes, the velocity of wreckage after a collision is affected by the mass of the objects involved. The larger the mass of the objects, the greater the impact and resulting velocity of the wreckage.

3. What other factors can affect the velocity of wreckage after a collision?

Aside from mass, other factors that can affect the velocity of wreckage after a collision include the speed and direction of the objects before impact, the type of collision (head-on, rear-end, etc.), and any external forces acting on the objects during the collision.

4. Can the velocity of wreckage after a collision be calculated for multiple objects?

Yes, the formula for calculating the velocity of wreckage after a collision can be applied to multiple objects. However, the calculation becomes more complex as the number of objects involved increases.

5. How accurate are the calculations for velocity of wreckage after a collision?

The accuracy of the calculations for velocity of wreckage after a collision depends on the accuracy of the initial data and assumptions made. In real-life scenarios, there may be other variables and external factors that can affect the accuracy of the calculation.

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