Gravitational Field Strength and Newton's Law of Gravitation

Module 5

Define Gravitational field strength

force F per unit mass m of an object at that point:

Equation for gravitational field strength?

relationship between F and m

Greater the mass of an object, the force is greater.

Factors that affect the gravitational field strength?

Radius of the planet

Mass of the planet

What is the equation for gravitational field strength in radial field.

What is the relationship between the gravitational field and the separation between the centres of mass?

As the separation increases, the field strength decreases.

g increases by a factors of

1/r²

1/r² = specification?

• if r = Radius of Earth, g is directly proportional to r

• if r =/ Radius of Earth. g is inversely proportional to r

What is Newton’s Law of gravitation?

The gravitational force F between two masses m₁ and m₂ is proportional to the product of their masses and inversely proportional to the square of their separation, r

Equation for Newton’s Law of gravitation

What to be careful when doing this calculation

The separation is squared and the distance between the centre of masses.

The field lines are __ when close to the surface of Earth

Parallel