Science Flash Cards (chpt. 8 and 9
Machine
A device with moving parts that work together to accomplish a task.
Work
A form of energy that comes from force applied over distance. A force of 1 newton does 1 joule of work when the force causes 1 meter of motion in the direction of the force. Work=Force*Distance
Gear
A rotating wheel with teeth that transfers motion and forces to other gears or objects.
Lever
A stiff structure that rotates around a fixed point called a fulcrum.
Watt (W)
A unit of power equal to one joule per second.
Simple Machine
An unpowered mechanical device that accomplishes a task with only one movement.
Output
Forces, energy, or power provided by the machine.
Input
Forces, energy, or power supplied to make a machine accomplish a task.
Power
The rate of doing work or moving energy. Power is equal to energy (or work) divided by time. Power=Work/Time
Mechanical Advantage
The ratio of output force divided by input force.
Gear Ratio
The ratio of output turns to input turns for a pair of gears.
Efficiency
The ratio of usable output work divided by total input work. Efficiency is often expressed as a percent, with a perfect machine having 100 percent efficiency.
Work Output
The work that an object does as a result of work input.
Work Input
The work that is done on an object.