Consider the Cavendish experiment in Figure 5.22. When he designed this experiment, Cavendish had to decide how large to make the spheres. If they are made larger, they will have a larger mass, which, according to Equation 5.16, will make the gravitational attraction larger and the force therefore easier to measure. If the spheres are made larger, however, the distance between their centers will necessarily increase, which makes the force smaller. Assuming the spheres in Figure 5.22 all have the same radii, suppose the value of r is increased by a factor of two. Will that change increase or decrease the force, and by what factor? Assume that the spheres all have the same constant density.

Figure 5.22

Light source Mirror - Fiber z p m1