machines

Work and Efficiency

- Work: The product of force and displacement in the direction of the force.

- Output work: The work done by the machine on the load.

- Input work: The work done on the machine to make it do work.

- Efficiency: The ratio of output work to input work, expressed as a percentage.

- Ideal machine: A machine with 100% efficiency, meaning that all of the input energy is converted to output energy.

- Real machine: A machine with less than 100% efficiency, meaning that some of the input energy is lost to friction or other factors.

Kinds of Levers

- Class 1 Lever: Fulcrum is in the middle, load on one side, and effort on the other.

- Class 2 Lever: Load is in the middle, fulcrum is on one side, and effort on the other.

- Class 3 Lever: Effort is in the middle, fulcrum is on one side, and load on the other.

Mechanical Advantage of Levers

- Mechanical advantage (MA) is the ratio of the output force to the input force.

- MA = effort arm / load arm

- Class 1 levers: MA can be greater than, equal to, or less than 1.

- Class 2 levers: MA is always greater than 1.

- Class 3 levers: MA is always less than 1.

Examples of Levers

- Class 1 lever: See-saw, crowbar, scissors

- Class 2 lever: Wheelbarrow, bottle opener, nutcracker

- Class 3 lever: Tweezers, tongs, forearm