Question 1
Question (a)
(a)
State what is indicated by the direction of the gravitational field line at a point in a gravitational field.
Question (b)
(b)
A large isolated uniform sphere has mass M and radius R.
Point P lies on a straight line passing through the centre of the sphere, at a variable displacement x from the centre, as shown in Fig. 1.1.
Fig. 1.1
Fig. 1.2 shows the variation with x of the gravitational field g at point P due to the sphere for the values of x for which P is inside the sphere.
Fig. 1.2
The magnitude of the gravitational field at the surface of the sphere is Y.
Question (i)
(i)
Explain why, at the surface of the sphere, g always has the opposite sign to x.