A loss in path as payment for a gain in force is a general law not only for levers but also for all other devices and mechanisms used by man.

A tackle is widely used for lifting loads. This is what we call a system consisting of several movable pulleys joined to one or several fixed pulleys. The load in Figure 1 is suspended by six strings. It is clear that the weight is distributed among the strings, and so the tension in a string will be six times less than the weight. The lifting of a one-ton load will require an application of \(1000/6 = 167\,\mathrm{kgf}\). However, it is not difficult to see that in order to raise the load by \(1\,\mathrm{m}\), one must haul in \(6\,\mathrm{m}\) of string. For raising the load by \(1\,\mathrm{m}\), \(1000\,\mathrm{kgf\cdot m}\) of work are needed. We must supply this work in “some form”—a force of \(167\,\mathrm{kgf}\) must act along a \(6\,\mathrm{m}\) path, a force of \(10\,\mathrm{kgf}\) along a \(100\,\mathrm{m}\) path, and a force of \(167\,\mathrm{kgf}\) along a \(1\,\mathrm{km}\) path.

An inclined plane, which we discussed here, is also a device permitting a gain in force at the expense of a loss in path.

A blow is a distinctive means of multiplying forces. A blow with a hammer, an axe, a ram and even a blow with a - fist can create an enormous force. The secret of a strong blow isn’t complicated. Driving a nail into an unyielding wall with a hammer, one must take a good wind-up. A big swing, i.e. a long path along which the force acts, generates a significant kinetic energy in the hammer. This energy is released along a small path. If the swing covers \(0,5\,\mathrm{m}\) and the nail enters \(0.5\,\mathrm{cm}\) into the wall, the force is intensified by a factor of 100. But if the wall is harder and the nail, after the same swing of the hand, enters \(0.5\,\mathrm{mm}\) into the wall, the blow will be ten times as strong as in the former case. The nail does not enter a hard wall as deeply, and the same work is expended on a shorter path. It turns out that a hammer works like an automaton: it strikes harder where the wall is harder.

If a hammer of \(1\,\mathrm{kg}\) is “speeded up”, it will strike a nail with a force of \(100\,\mathrm{kgf}\). Also, in splitting logs with a heavy wood-chopper, we break the wood with a force of several thousands ’s. Heavy forging hammers fall from small heights, of the order of a metre. Flattening a forged piece by 1 mm–2 mm, a hammer of \(1000\,\mathrm{kg}\) comes down on it with an enormous force, that of \(1\times 10^{6}\,\mathrm{kgf}\).