Gravitational Fields

These flashcards cover key concepts related to gravitational fields, gravitational potential, Newton's law of gravitation, and their implications.

What is the gravitational field strength (g)?

It is the force per unit mass acting on a small test mass placed in the field, expressed in N/kg.

Define a radial field.

A radial field is where the gravitational field lines are directed to the center of the mass, such as the force on a small mass near a spherical body always acting towards the center.

Define a uniform field.

A uniform field is one where the gravitational field strength is the same in magnitude and direction throughout the field, with parallel and equally spaced field lines.

How does gravitational potential vary with distance from a mass?

Gravitational potential decreases as the distance from the mass increases and is inversely proportional to that distance.

What is gravitational potential energy (gpe)?

Gravitational potential energy is the energy an object possesses due to its position in a gravitational field.

What happens to gravitational field strength as distance from a mass increases?

Gravitational field strength decreases with increasing distance from the mass according to the inverse-square law.

What is the significance of Newton's law of gravitation?

It describes the attractive force between two masses and states that this force is proportional to the product of the masses and inversely proportional to the square of the distance between them.

What is the escape velocity?

The minimum velocity an object must achieve to break free from a planet's gravitational pull.

What is Kepler's third law?

It states that the square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit.

What is an equipotential surface?

It is a surface on which the gravitational potential is constant, meaning no work is done when moving along the surface.

What is the formula for gravitational force between two masses?

F = G(m₁m₂/r²), where F is the gravitational force, G is the gravitational constant, m₁ and m₂ are the masses, and r is the distance between the centers of the two masses.

How is gravitational potential defined?

Gravitational potential at a point is defined as the work done per unit mass to move a small object from infinity to that point.

What effect does height have on gravitational potential energy?

As height increases, gravitational potential energy increases, meaning a mass raised in a gravitational field gains energy.

What is the difference between gravitational field strength and gravitational potential?

Gravitational field strength is the force per unit mass, while gravitational potential is the energy per unit mass related to position in the field.

Describe how gravitational potential energy changes as one moves away from a planet.

Gravitational potential energy becomes less negative (increases) as the distance from the planet increases.

What role does gravitational potential energy play in rocket launches?

A rocket must do work against the gravitational potential energy of a planet to ascend and escape its gravitational field.

How do you calculate the work done to increase gravitational potential energy?

Work done (W) is equal to the change in gravitational potential energy (Δgpe). W = mΔV, where m is the mass and ΔV is the change in gravitational potential.