1) Planet P has mass M, radius R, and surface gravitational field strength g. Planet Q has mass 4M and radius 2R.
What is the surface gravitational field strength of Q?

2) [latexpage]

The Earth may be taken to be a uniform sphere of radius r. The gravitational field strength at its surface is g.

What is the gravitational field strength at a height h above the surface?

A $\frac {gr^2}{(r+h)^2}$

B $\frac {gr}{(r+h)}$

C $\frac {g(r-h)}{r}$

D $\frac {g(r-h)^2}{r^2}$

3) Two point masses, 4M and M, are separated by a distance 2r. What is the resultant gravitational field strength at their midpoint?

4) A 4.0 kg object is placed in a gravitational field of strength 3.0 N kg⁻¹. What is the gravitational force on the object?

5) The Earth has a radius of 6.38 × 10⁶ m, and rotates on its axis once every 24 hours. At what latitude (i.e., the angle θ in the drawing) is the tangential speed one third that of a person living at the equator? Take the mass of the Earth to be 6.0 × 10²⁴ kg.