Conservation of Momentum with Collisions

In summary, the question asks for the velocity of a diesel engine and freight car combination after a collision. The engine weighs 8 times more than the car and both were initially moving in the same direction. Using the equation V= mdvd + mfvf over M, with the sub d representing the diesel engine and sub f representing the freight car, the final velocity can be calculated as 5 km/h if the mass of the car is represented as m and the mass of the engine is 8m.
  • #1
Sadiebunkins
1
0

Homework Statement



A diesel engine weighs 8 times as much as a freight car. This diesel engine, moving on a horizontal track at 3 km/h, crashes into the freight car (which was moving at 2 km/h in the same direction). What is the velocity, in km/h, of the now linked together engine/car combination? You may assume no numerical values not given.

Homework Equations



V= mdvd + mfvf over M or md + mf

The sub d is for diesel engine
The sub f is for freight car

The Attempt at a Solution


I am not really sure is the m's cancel and all that is left with is the v's. If so the final velocity would be 5 km/h
 
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  • #2
Try calling the mass of the car m and then write the mass of the engine as 8m. You might be able to see what ends up canceling afterward.
 

Related to Conservation of Momentum with Collisions

1. What is conservation of momentum with collisions?

Conservation of momentum with collisions is a fundamental principle in physics that states that the total momentum of a closed system remains constant before and after a collision. This means that the total momentum of all objects involved in the collision is the same before and after the collision occurs.

2. How is momentum conserved in a collision?

In a collision, momentum is conserved through the exchange of forces between the colliding objects. During the collision, the objects exert equal and opposite forces on each other, resulting in a transfer of momentum from one object to the other. This transfer of momentum ensures that the total momentum of the system remains constant.

3. What types of collisions conserve momentum?

All types of collisions, including elastic and inelastic collisions, conserve momentum. In an elastic collision, both kinetic energy and momentum are conserved, while in an inelastic collision, only momentum is conserved. However, in both cases, the total momentum of the system remains constant.

4. How is conservation of momentum used in real-world applications?

Conservation of momentum is used in many real-world applications, such as in car crashes and sports. In car crashes, engineers use the principle of conservation of momentum to design safer cars and reduce the impact force on passengers. In sports, players use the principle to maximize their momentum and achieve better performance, such as in ice skating and diving.

5. What are the limitations of conservation of momentum?

Conservation of momentum is a fundamental law of physics and is valid for all closed systems. However, it does have its limitations. This principle assumes that there are no external forces acting on the system, and it only applies to isolated systems. In real-world situations, there may be other factors at play that can affect the momentum of a system, such as friction and air resistance.

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