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Can a body change in momentum without changing in kinetic energy?
Wiki User
∙ 13y ago
Kinetic energy = 1/2mv2
momentum = mv.
If you could change the mass at the same time as the velocity to keep the kinetic energy constant, then you could change momentum without changing the kinetic energy.
Suppose you have a mass of 4kg moving at 1m/s ... it has a momentum of 4 units (N-s) and a Kinetic Energy of 2 units (Joules).
The mass could be burned to make the craft go faster .. say that it increased its speed to 2m/s but in the process the mass decreased to 1kg .. the Kinetic energy would still be 2 Joules, but the momentum would now be 2 units. (not a very efficient engine, this).
Another burn of the mass, and now it only weighs 0.5kg .. however the speed has increased to 2*(sqrt(2)) m/s, KE is still 2J, and momentum is now .. Sqrt(2) N-m ..
Provided your destruction of mass occurred at the correct rate as the velocity changes, yes you can change momentum without changing kinetic energy. Just not arbitrarily.
Wiki User
∙ 13y ago
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What are ways of changing momentum?
You change momentum by changing mass or, more commonly, velocity.
Is it possible to change translational kinetic energy of an object without changing it rotational energy?
yes
How does kinetic energy change when the momentum is doubled?
energy is quadrupled
How do you cause a change in momentum?
Usually by changing the velocity.
Can kinetic energy cause changes?
kinetic energy can change momentum of the body if any external force exist
How does the kinetic energy of a body change if its momentum is halved?
Since momentum is proportional to the velocity, half the momentum means half the velocity (and therefore half the speed). And since kinetic energy is proportional to the SQUARE of the speed, half the speed means 1/4 the kinetic energy.
Does an object with momentum always have energy?
Not if it's potential energy. Only objects with kinetic energy have momentum.
How does the law of conservation of momentum relate to work?
It relates to work in the sense that work involves moving things, which involves changing their momentum, and to change momentum you have to create an equal and opposite momentum so that momentum is conserved - although the planet Earth is such a convenient momentum sink that in most cases this happens without being specifically noticed.
Example of electrical energy changing to chemical energy to kinetic energy?
how can you change potencial energy to kinetic energy
Does kinetic energy actually increase the speed of an object?
Gaining kinetic energy 'E' amounts to saying that the momentum of an object increases. E = p^2 / 2m where p is momentum and m is mass. (Momentum is just mass times speed.) So, to increase the speed the kinetic energy has to change. In other words, if you set the kinetic energy to any value you like and keep it constant, there won't be a speed up. What is the change in kinetic energy? You can just as well ask what is the change in momentum. Physicists have chosen the latter question and call the change in momentum 'the force'. F = dp / dt where F is force and d/dt means derivation with respect to time. It is the pushing force acting on objects that makes them gain speed. Kinetic energy is usually something that you calculate at the end when you have found out what the forces in your problem are and what the momentum is as a function of time.
Is changing direction really the same as changing speed?
No. It is possible to change direction without changing speed. However, it is not possible to change direction without changing velocity.
How do the area and perimeter of the area of a figure change when it's dimensions change?
The answer depends entirely on how the dimensions change. It is possible to change the dimensions without changing the perimeter. It is also possible to change the dimensions without changing the area. (And it is possible to change the area without changing the perimeter.)
