Conservation of momentum (should be easy)

In summary, an object with a mass of 16 kg and a speed of 19 m/s explodes into two pieces, with one piece being 4 times as massive as the other. The explosion occurs in deep space and the less massive piece stops relative to the observer. The amount of kinetic energy added to the system during the explosion, as measured in the observer's reference frame, is 722J. This is calculated by using the formula for initial and final kinetic energy, with the final momentum being correctly calculated as 23.75 m/s.
  • #1
gbdusty
9
0
An object, with mass 16 kg and speed 19 m/s relative to an observer, explodes into two pieces, one 4 times as massive as the other; the explosion takes place in deep space. The less massive piece stops relative to the observer. How much kinetic energy is added to the system during the explosion, as measured in the observer's reference frame?

I calculated the original momentum, then i calculated the final momentum. I then solved for vfinal. I got 23.75 m/s for my vfinal. But now I tried calculating delta KE and I'm getting 1624.5 J, but my homework site is telling me it is incorrect. Can someone help me out?
 
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  • #2
I believe that your vfinal is correct, but you have probably made some stupid mistake with calculations at the end.
Initial kinetic energy is 0.5*16*(19)^2 and final KE is 0.5*(16/5)*4*(23.75)^2, and the difference, delta KE is 722J. Check it again!
 
  • #3
Are you using the correct formula?
 
  • #4
thanks i was adding both masses for the final momentum, that was my foolish mistake.
 

Related to Conservation of momentum (should be easy)

1. What is conservation of momentum?

Conservation of momentum is a fundamental law of physics that states that the total momentum of a system remains constant unless acted upon by an external force. In simpler terms, it means that the total amount of motion in a closed system does not change over time.

2. How is momentum calculated?

Momentum is calculated by multiplying an object's mass by its velocity. The formula for momentum is: p = mv, where p is momentum, m is mass, and v is velocity. Momentum is measured in units of kg * m/s.

3. What is an example of conservation of momentum in action?

One example of conservation of momentum is when a billiard ball collides with another billiard ball. The first ball has a certain amount of momentum before the collision, and after the collision, that same amount of momentum is distributed between the two balls.

4. Does conservation of momentum only apply to objects in motion?

No, conservation of momentum can also apply to stationary objects. For example, if a stationary object is struck by a moving object, the stationary object will gain momentum while the moving object will lose the same amount of momentum.

5. Are there any exceptions to the law of conservation of momentum?

Yes, there are a few exceptions to the law of conservation of momentum. One exception is in the case of nuclear reactions, where a small amount of mass is converted into energy. Another exception is in extremely high-speed or small-scale interactions, where quantum mechanics comes into play and can cause deviations from the law of conservation of momentum.

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