G. Field

Question 1

Explain why the gradient of the graph near the surface of Earth and that near the
surface of Moon have opposite signs. (Potential graph)

Answer 1

1) The gradient of the potential –displacement graph gives the
a) gravitational field strength,
b) a VECTOR thus, the sign indicates the direction of the gravitational field strength.

2) Near the earth, the net gravitational force is directed TOWARDS the earth due to larger
influence of earth (larger mass and smaller distance) than moon while near the moon,

Question 2

Explain why gravitational potential is always negative

Answer 2

Gravitational potential at infinity defined as ZERO

and since gravitational force is
attractive, work done by external agent as object moves from infinity to a point in
the gravitational field so potential is negative.