Leverage Russian style
Jearl Walker www.flyingcircusofphysics.com
March 2014 Here are two examples in which leverage is cleverly used in Russia. In the first we see a car rescued from an ice covered water body. The car is almost completely submerged in the ice. Bringing a heavy tow truck out onto the ice to pull the car free would have disastrous. Instead, enough of the ice is cracked in order to slip a wood frame under the rear of the car and loop ropes around the rear wheels. A rope then runs back to the heart of the operation: The rope wraps around a pole that has been driven into the ice. A long horizontal pole is attached to the vertical pole. Several men push the horizontal pole around and around in order to wrap up the rope onto the vertical pole. As the rope wraps up, the car is gradually pulled up and out of the ice. If the men had pulled directly on the rope, they would have been unable to pull the car out by even a little bit.
Instead, they used leverage. Rotating the vertical pole required a large torque. They provide that torque by pushing on the horizontal pole with a modest force. The clever part is that they applied their push at a large distance from the vertical pole. Since their torque is the product of force and distance from the rotation axis, their torque was large.
Here is another Russian clever use of leverage. Logs are to be loaded onto a truck, but the logs are so heavy that manual loading would require several men. Instead, a metal pole is attached to the rear wheel of the truck such that as the wheel rotates when the truck moves forward, the log is pulled by a rope attached to the outer end of the pole. The rotating wheel applies a large torque to the inner end of the pole, which then applies a torque to the outer end, pulling up the pole.