HSC · Physics · Motion in Gravitational Fields · also VCE Gravity & Gravitational Fieldslive from the app
Gravitational Potential Energy and Potential
The formula is E = -GMm/r where the negative sign shows that energy must be added to escape to infinity where E = 0. Gravitational potential V = -GM/r is the energy per kilogram at that point, independent of the test mass.
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physics · motion in gravitational fields · gravitational potential energy and potentialdrag it · it is yours
the one idea
why this one carries the topic.
An orbit is just falling — the object accelerates toward the mass forever but keeps missing because it's moving sideways fast enough. Kepler's laws aren't three facts to memorise; they're what falling-forever forces on any orbit: the geometry, the sweeping, and the fixed link between period and radius.
Gravitational potential energy is negative because work must be done against gravity to separate masses to infinity where potential energy is defined as zero, with the system naturally moving toward lower (more negative) energy states.
what examiners catch — Examiners frequently test whether students can distinguish between potential V (energy per kilogram, J/kg) and potential energy E (total energy, J), particularly when calculating escape velocities or orbital energies.
what you leave with
three things, not forty.
GPE increases as you move away from a mass, becoming less negative and approaching zero at infinity
Work must be done against gravity to increase GPE when lifting an object
The change in GPE equals the work done, and near Earth's surface this simplifies to the familiar mgh formula
what's underneath
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this conceptgravitational potential energy and potentialGravitational potential energy is negative because work must be done against gravity to separate masses to infinity where potential energy is defined as zero, with the system naturally moving toward lower (more negative) energy states.
sits under itgravitational field strengthbecause potential is the field, accounted in energy
sits under itwork, energy and the conservation principlebecause potential energy is defined through work
the rest of motion in gravitational fields
3 more, same treatment.
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gravitational field strengthin the appnewton's law of gravitationin the apporbital motion and kepler's lawsin the app
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