Gravitational Fields Complete A level Flashcards
Definition a gravitational field strength?
The force per unit mass acting on a small test mass in a field
What are the units for gravitational field strength?
n/kg or m/s^-2
What does a field line show?
The direction in which a small test mass would move if placed in the field.
What is the difference between a radial field and a uniform field?
Magnitude of g decreases with distance but in uniform, g is constant, represented by equally spaced out lines.
What is Newton’s law of gravitation?
Force between 2 objects is always an attractive force, and is proportional to the product of both masses, and inversely proportional to r^2. Follows an inverse square law.
What is gravitational potential energy?
The energy of an object due to its position in a gravitational field.
What is reference point for G.P.E?
Zero gpe at infinity. Work must be done to escape the gravitational field strength. Field does negative work on an object when bringing it to a point from infinity as gravity is attractive force.
What is gravitational potential? What is its units?
At a point in a field, its the work done per unit mass to move a small object from infinity to that point. j/kg
What is an equipotential? Give its features.
A surface of constant potential. No work is done when moving along an equipotential surface. They are at right angles to the field lines.
What else can gravitational field strength be called?
The negative of the potential gradient.
What does closer equipotentials show?
A stronger gravitational field strength.
What does the area under the field strength vs distance curve represent?
Potential. To get potential energy, multiply by the mass.
Whats is the escape velocity?
The minimum velocity required for an object to escape the gravitational field.
How can you derive escape velocity equation?
Set KE = GPE and solve for v.
What does the gradient of a potential vs distance curve give us?
Gravitational field strength at a point.
