Draw a graph of the strength of the gravitational field,g, against the distance r from the centre of mass of an object.
Inverse square law
What is gravitational potential energy of a mass
It is the work that would need to be done to move it against the force of gravity.
What is the equation for the gravitational potential energy of a mass,m?
Egrav = -GMm/r
Draw the graph of gravitional potential energy vs r to show how the gravitational potential energy varies for Earth.
- What does the gradient of the graph show?
- What is the potential energy at an infinite distance from Earth?
- The gradient of a tangent to the graph gives the value of the gravitional force at that point. The force is greatest at the Earth's surface.
- Potential energy is zero at an infinite distance from the Eartch.
What is gravitional potential at a point,V?
It is the potential energy per unit mass, V = Egrav/m .
In a radial field, what is the equation for gravitiational potential at a point,V?
V = - GM/r
Draw the graph of gravitational potential vs r, for a point mass r distance away.
- The gradient of the graph tells you what?
- When is the gravitational potential zero?
- The graident of a tangent to the graph gives the value of g at that point.
- The gravitiational potential,V, is zero at infinity.
What are equipotentials?
Equipotentials show all the points in a field which has the same potential.
What is the gravitational potential at the Earths surface?
What is the equation that gives the linear velocity of a circular orbit of planets due to the centripetal force of gravitational force?
v = (GM/r)1/2
It comes from equation F = - GMm/r2 and F = mv2/r