How is conservation of momentum and energy used?

Question

I would like it if you could use it with elastic and inelastic collisions. When is momentum lost or gained in either collision, when is energy gained in either collision. What IS conservation of momentum and what IS conservation of energy

Answer 1

Conservation of energy and momentum basically means that energy is never created or destroyed, and same with momentum. It has to come with somewhere. If energy or momentum leaves one system, it must enter another system. If energy appears in a system, it had to have come from one. Momentum is never really gained or lost, and same with energy -- it is simply transfered from one body to another. An elastic collision is one in which no kinetic energy is lost, all of it is transfered directly from one system to another.. In an inelastic collision, some of the energy is transfered to a third system (via sound waves, heat energy, or other such energy loss). In this case of an inelastic collision, the total kinetic energy of the two bodies before, is not the same as it is afterwards. The difference in these values would be the energy "lost" from these systems that was tranfered elsewhere.

Answer 2

In a closed system (say 2 objects colliding) momentum before is always equal to momentum after whether or not it's an elastic collision.

Kinetic energy is conserved ONLY in an elastic collision. Erik's statements are somewhat confusing as he waffles about kinetic vs total energy in the system. When some (or even all) of the KE is turned to heat, the movement of the objects is strongly affected.

Consider 2 identical objects colliding head-on with the same speed. The momentum is zero because V1 = -V2. They have lots of KE because the KE formula has V² in it. If it's an elastic collision, they have the same KE afterward and the momentum is still zero. If an inelastic collision, all the KE is turned into heat and V1 = V2 = 0

Answer 3

Conservation of energy can only be used for ELASTIC collisions. For inelastic collisions, energy is converted to deformation and unless you know how much energy has been converted, you can't use conservation of energy.

Conservation of momentum can be used for both elastic and inelastic collisions. It must be used in a vectorial manner when collisions can occur in two-dimenional or three dimensional space, and momentum is conserved in each dimension. Momentum is the product of mass and velocity, and velocity is a vector, not a scalar, that is it has direction, whereas "speed" is a scalar quantity (does not have direction associated with it).

Energy is neither created or destroyed, it can only be converted from one form to another - conservation of Energy.

The product of the mass before and the velocity before a collision is the same as the product of the mass after and the velocity after a collision - conservation of momentum.

Answer 4

In reality perfect elastic collison does not exist in complex mass structures.
Conservation of momentum is only an aproximation . According to Einstein relativity ,momentum is not conserved because mass in the theory is supposed to increase with velocity.
Mass increases faster than velocity so momentum is not conserved in relativity.
In collison there is an energy loss so the total energy before collision is not the same as the total energy after collision.

Answer 5

the reason being this issue consists of a rolling merchandise. once you study approximately rotation, you will understand that rolling gadgets contain a "rotational' kinetic potential. hence this is plenty easier to handle momentum(mass x velocity). Momentum is conserved inspite of variations in potential. i'm hoping this helps.