Principle of conservation of momentum question

In summary, somebody help explain how to do this for me, am not looking answer, an explanation so i can solve it would be great.
  • #1
dansbr
10
0
1. Somebody help explain how to do this for me, am not looking answer, an explanation so i can solve it would be great.

A space vehicle traveling at a velocity of 7000km/h separates into two sections of mass 1100kg and 200kg. the two parts continue moving in the same direction with the lighter section moving at 10000km/h.

Determine the velocity of the heavier section after separation
The change in the total kinetic energy of the system



2. I know to use the conservation of momentum (M1U1 + M2U1 = M1V1 + M2V2), but since there are three values for mass am not sure where to begin.



3. any attempt i have made has been unsuccessful

Cheers :)
 
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  • #2
What's the mass and velocity of the space vehicle before it breaks up?
 
  • #3
the space vehicle is traveling at 7000km/h. i don't know the mass of it but wouldn't it be the sum of the sections so 1100+200=1300kg
 
  • #4
dansbr said:
the space vehicle is traveling at 7000km/h. i don't know the mass of it but wouldn't it be the sum of the sections so 1100+200=1300kg
Exactly. So now you have one side of the momentum conservation equation. Set the initial momentum (of the intact vehicle) equal to the sum of the momenta of the sections after it breaks up.
 
  • #5
So if momentum is f=mv
Would the momentum of the intact vehicle be (200x10000)+(1100x v?)
Am still not sure about this
 
  • #6
dansbr said:
So if momentum is f=mv
Would the momentum of the intact vehicle be (200x10000)+(1100x v?)
Am still not sure about this
The momentum of the intact vehicle is its mass (which you figured out already) times its velocity (which is given).
 
  • #7
So the momentum of the intact vehicle is 1300x7000=9100000
Does that mean the sum of the momentums of the separate parts equal the momentum of the intact vehicle.
 
  • #8
That's what conservation of momentum is about.
 
  • #9
dansbr said:
So the momentum of the intact vehicle is 1300x7000=9100000
Does that mean the sum of the momentums of the separate parts equal the momentum of the intact vehicle.
Exactly. When something is "conserved" that means it stays the same. The total momentum of the of the vehicle (or its parts) doesn't change when it breaks up.
 
  • #10
Is the answer 6454km/h
 
  • #11
dansbr said:
Is the answer 6454km/h
Looks right.
 
  • #12
Then would the change in kinetic energy of the system be the kinetic energy of the intact vehicle minus the kinetic energy of the heavier of the two separate bits?
 
  • #13
dansbr said:
Then would the change in kinetic energy of the system be the kinetic energy of the intact vehicle minus the kinetic energy of the heavier of the two separate bits?
Not exactly. The change in KE is the total KE after the break up (both pieces) minus the initial KE (of the intact vehicle).
 
  • #14
Thanks good help
 

FAQ: Principle of conservation of momentum question

1. What is the principle of conservation of momentum?

The principle of conservation of momentum states that the total momentum of a closed system remains constant. In other words, the total amount of momentum before a collision or interaction is equal to the total amount of momentum after the collision or interaction.

2. Why is the principle of conservation of momentum important?

The principle of conservation of momentum is important because it is a fundamental law of physics that helps us understand and predict the behavior of objects in motion. It is also essential for understanding phenomena such as collisions and explosions.

3. How is the principle of conservation of momentum related to Newton's third law of motion?

The principle of conservation of momentum is closely related to Newton's third law of motion, which states that for every action, there is an equal and opposite reaction. This means that when two objects interact, the forces they exert on each other are equal and opposite, resulting in a transfer of momentum between the objects.

4. Can the principle of conservation of momentum be violated?

No, the principle of conservation of momentum cannot be violated in an isolated system. This means that in a closed system where there is no external force acting on the objects, the total momentum will always remain constant.

5. How is the principle of conservation of momentum applied in real-life situations?

The principle of conservation of momentum is applied in many real-life situations, such as car crashes, sports, and rocket propulsion. It helps engineers design safer cars and predict the trajectory of objects in motion, and it also helps athletes understand how to use momentum to their advantage in sports like gymnastics and ice skating.

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