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THE ADAMSON LECTURE

Fig. 1.

explained the behaviour of the system by assuming an attractive force with corresponding potential energy between A and B. This is due to our considering A and B as a complete system, whereas it is in reality part of a larger system, and when we consider the complete system we see that it behaves as if it were acted on by no forces and possessed no energy other than kinetic.

It may perhaps be of interest to note that we can in a similar way make two bodies appear to attract each other with a force varying inversely as the square of the

Fig. 2.