we consider forces applied to objects of constant mass. How would the situation change if a system is added or removed while a force is being applied? Give examples of situations where this could happen.
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We start from the concept of linear momentum.
P = m v
The derivative of the linear momentum is the force.
F = dp / dt = dm / dt. V + m. Dv / dt = dm / dt. V + m a (derived from a product)
The value dm / dt is the mass change per unit time.
If you gain mass dm / dt is positive. If it loses mass, it is negative. We are left in the latter case:
F = -dm / dt. V + m a
Example for a mass loss.
When an artificial satellite is put into orbit, the rocket that drives it loses mass (fuel) to a large ratio, which is measured in kilograms per second (mass variation)
Example for a mass gain.
A conveyor belt receives charge at the rate of a few kilograms per second. For the design of the tape, it must be taken into account that mass gain, which occurs at the beginning of the transport.
P = m v
The derivative of the linear momentum is the force.
F = dp / dt = dm / dt. V + m. Dv / dt = dm / dt. V + m a (derived from a product)
The value dm / dt is the mass change per unit time.
If you gain mass dm / dt is positive. If it loses mass, it is negative. We are left in the latter case:
F = -dm / dt. V + m a
Example for a mass loss.
When an artificial satellite is put into orbit, the rocket that drives it loses mass (fuel) to a large ratio, which is measured in kilograms per second (mass variation)
Example for a mass gain.
A conveyor belt receives charge at the rate of a few kilograms per second. For the design of the tape, it must be taken into account that mass gain, which occurs at the beginning of the transport.
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