Physics

Problem

A moon

M

orbits a planet

P

. The gravitational field strength at the surface of

P

due to

P

g_P

. The gravitational field strength at the surface of

M

due to

M

g_M

. For

M

and

P

\frac{\text{radius of } M}{\text{radius of } P} = 0.27

and

\frac{\text{mass of } M}{\text{mass of } P} = 0.055

(a) Determine

\frac{g_M}{g_P}

. (b) Point O lies on the line joining the centre of M to the centre of P. ![](https://storage.googleapis.com/diraq-contents/PROD/homework-question-parsing/marker/20260306T054047Z/2585026ebe03407db2a812cc958fc291/a2941437086c9bc688719d26ad7e6d01_img.jpg) The graph shows the variation of gravitational potential

V

with distance

x

from the surface of P to O. The gradient of the graph is zero at point O. (b.i) State and explain the magnitude of the resultant gravitational field strength at O. (b.ii) Outline why the graph between P and O is negative. (b.iv) The gravitational potential due to the mass of

M

at the surface of

P

can be assumed to be negligible. Estimate, using the graph, the gravitational potential at the surface of

M

due to the mass of

M

. (b.v) Draw on the axes the variation of gravitational potential between

O

and

M

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