#2: Gravitational Potential

These flashcards cover key concepts related to gravitational potential and fields, including definitions, calculations, and relations between potential and gravitational energy.

What is gravitational potential?

Gravitational potential is defined in terms of work done per unit mass to move a small object from infinity to a point in a gravitational field.

How is the change in gravitational potential energy (gpe) calculated when moving between two points?

The change in gravitational potential energy is given by AE = m(V₂ - V₁), where V₁ and V₂ are the gravitational potentials at the two points.

Where is the position for zero gravitational potential energy?

The position for zero gravitational potential energy is at infinity, where the gravitational force is negligible.

What does the gravitational potential at a point depend on?

The gravitational potential at a point is the work done per unit mass to move a small object from infinity to that point.

What is the unit of gravitational potential?

The unit of gravitational potential is Jkg⁻¹.

What is the gravitational potential at the surface of a planet if it is given as -100 MJ kg⁻¹?

The gravitational potential at the surface of the planet is -100 MJ kg⁻¹.

For a payload mass of 1000 kg at -100 MJ kg⁻¹, how much work is needed to escape the planet's gravitational field?

The work needed to escape is at least 100000 MJ to increase the gravitational potential to zero.

What does an equipotential surface represent?

An equipotential surface represents areas of constant gravitational potential where no work needs to be done to move along it.

How does the gravitational potential gradient vary with distance from the Earth's surface?

The potential gradient near the Earth's surface is constant at 9.8 Jkg⁻¹m⁻¹ but decreases with greater distances away from the surface.

How is gravitational field strength related to the potential gradient?

Gravitational field strength g is the negative of the potential gradient, represented as g = -ΔV/Δr.