difference between law of conservation of energy and law of conservation of momentum.
Answers
Imagine a block of wood resting on two supports at each end. You point a gun upward under the block and shoot the block upwards.
One scenario is you shoot the block upwards in the exact center. Another scenario is you shoot upwards near one of the support ends. The block is thick enough that in both cases the bullet comes to rest inside the block.
Question: in which case does the centre of mass of the block rise the highest?
Doing this problem shows you that you get a different answer if you use conservation of energy vs. conservation of momentum.
Main question: when teaching students dynamics is there a prescription you can give them to make it clear when and when not to use conservation of energy?
This example shows you that conservation of momentum applies, but there is not enough information in the question to successfully use conservation of energy (because you don't know how much the bullet heats up the block). Are there problems where conservation of energy works, but conservation of momentum becomes a problem? Or is it always the other way around? Why?
Explanation:
When two cars hit each other in an accident then the law of conservation of momentum is followed. ... This is on account of conservation of angular momentum. now about energy conservation,in every field and everywhere total energy is going to be conserved as its fundamental law of nature.
When do we use conservation of momentum vs. conservation of energy?
Imagine a block of wood resting on two supports at each end. You point a gun upward under the block and shoot the block upwards.
One scenario is you shoot the block upwards in the exact center. Another scenario is you shoot upwards near one of the support ends. The block is thick enough that in both cases the bullet comes to rest inside the block.
Question: in which case does the centre of mass of the block rise the highest?
Doing this problem shows you that you get a different answer if you use conservation of energy vs. conservation of momentum.
Main question: when teaching students dynamics is there a prescription you can give them to make it clear when and when not to use conservation of energy?
This example shows you that conservation of momentum applies, but there is not enough information in the question to successfully use conservation of energy (because you don't know how much the bullet heats up the block). Are there problems where conservation of energy works, but conservation of momentum becomes a problem? Or is it always the other way around? Why?
Dynamics
Mechanics
Ballistic Impact
Mechanical Engineering
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we use conservation of momentum when momentum is transferred by one thing to another to conserve it. first object loses its momentum while another gets its momentum so finally momentum is conserved.in your example as bullet strikes to wooden block,it loses its momentum but now wooden block gets its momentum so finally as much momentum was lost by bullet, same amount momentum is gained by wooden block. even its also of two types-linear and angular momentum of conservation.
some another examples will help you to understand better-
linear momentum conservation-
-When atoms collide with each other the law of conservation of momentum is followed.
-When the bullet hits the wooden block the law of conservation of momentum is followed and the block rises to a particular height.
-When two cars hit each other in an accident then the law of conservation of momentum is followed.
-When a baseball is hit by the bat the law of conservation of momentum is followed.
-When two runners collide in a race then the law is followed.
-Two billiard balls colliding with each other.
angular momentum conservation-
-During skating if the skater folds his or her hands then he is able to rotate at a greater speed as compared to when he opens his hands wide. This is on account of conservation of angular momentum.
now about energy conservation,in every field and everywhere total energy is going to be conserved as its fundamental law of nature. in your case kinetic energy of bullet is going to be converted in kinetic energy of wooden block and some heat energy also due to friction between bullet and wooden block, so finally total energy is conserved.