SAT® Subject Test in Physics

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Force between Lumps of Clay


Two spherical lumps of clay attract each other with some small amount of gravitational force, as explained by Newton's law of universal gravitation.

If I add clay to one lump and to the other so that the mass of one is 5 times as much as before and the mass of the other is 3 times as much as before, and I move the lumps (still spherical) so that their centers are now 4 times as far apart as before, how does the new gravitational force between them compare?


The new force is slightly smaller.


The new force is slightly greater.


The new force is more than 3 times as great.


The new force is less than one-third as great.


We cannot answer this question without knowing the universal gravitational constant.