10TH GRADE · CONSERVATION LAWS
Momentum and its conservation
Body impulse, force impulse and closed system.
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Basic Concepts
Closed system
A system of bodies, the external influence on which can be neglected in the problem under consideration.
The system boundaries are chosen so that the external impulse during the process is small. Then the interactions within the system do not change its total momentum.
Law of conservation of momentum
The total momentum of the closed system remains constant.
The vector sum of the impulses before the interaction is equal to the sum after it, if the external impulse can be neglected.
Physical quantities
Body impulse
Vector measure of the mechanical motion of a body.
Unit: kilogram-meter per second ·
Momentum change
The difference between the final and initial impulses.
Unit: kilogram-meter per second ·
Time lapse
The duration of the force.
Unit: second ·
Lesson formulas
Body impulse
Momentum is equal to mass times velocity.
Pulse unit
Impulse is measured in kilogram meters per second.
Force through change in momentum
Force is equal to the rate of change of momentum.
Impulse force
The impulse of force is equal to the change in the momentum of the body.
Conservation of momentum of two bodies
The total momentum of two bodies before interaction is equal to the total momentum after it.
Condition: The system is closed or the impulse of external forces can be neglected.
Related formulas
The same formulas in the reference, with symbols and units.
Tasks on the topic
Statements, answer options and the walkthrough.