Manchester Memoirs, Vol. xlvi. (1901), No. 3. 7 



After a lapse of two intervals of time (2/), the first block 

 will have travelled to a distance 



— v/^+^-<; 



III \2 J 



while block 2 has travelled a distance Zi, the increased 

 distance between the two being 



IP.a 



L = t, 



V m 



After lapses of n intervals of time n blocks will have 

 been released, and will be separated from each other 

 by distances L. As there are now no external forces 

 acting in these blocks, they will continue to occupy their 

 relative positions, and may therefore be looked upon as 

 one object. 



Before enquiring into the question of speed, it is 

 desirable to explain the meaning of the product P .a \ 

 this is twice the energy stored up in the spring, and, as 

 regards any of the above results, it is clear that it makes 

 no difference whether P, the pressure of the spring, is 

 constant until spring i leaves block 2, or whether it 

 gradually diminishes to nothing when separation takes 

 place, that being the case illustrated above ; nor is it 

 necessary that separation should take place, provided 



only that the total energy expended by the spring is — ^. 



Assuming now that separation does not take place, and 

 that the pressure P diminishes to O, then 



V m 



This is true, however small we make the distance (J+a), 

 provided t is reduced in proportion, nor does it make any 

 difference if, instead of a block and spring, we use elastic 

 blocks in contact with each other. This is of course the 



