Chapter 12 Work And Energy Flashcards
Work
The transfer of energy to a body by force that causes the body to move in the direction of the force.
Power
A quantity that measures the rate at which work is done or energy is transformed.
Mechanical Advatage
A quantity that measures how much a machine multiplies force or distance.
Joule
Newton’s•meters. Unit for work.
Watt
Unit of measure for power. A watt is the amount of power required to do 1 joule of work for 1 second.
Simple Machines
One of the six basic types of machines, which are the basis for all other forms of machines.
Compound Machines
A machine made of more than one simple machine.
Lever
Has a rigid arm that turns a point called the fulcrum.
First Class Lever
Has a fulcrum located between two points of application of input and output forces
Second Class Lever
The fulcrum is at one end of the arm and the input force is applied on the other end.
Third Class Lever
Multiply distance rather than force. Mechanical advantage of less than 1.
Pulley
Works like a Lever. The middle point of the pulley is like the fulcrum. The rest behaves like the arm of a lever.
Block and Tackle
Multiple pulleys put together in a single unit.
Wheel and Axle
Like a lever or pulley connected to a shaft. When the wheel is turned, the axle also turns.
Inclined Plane
Turns a small input force into a large output force by spreading the work out over a large distance.
Wedge
A modified inclined plane. Using a wedge is like pushing a ramp rather than pushing an object up a ramp.
Screw
An inclined plane wrapped around a cylinder.
Potential Energy
The energy that an object has because of its position, shape, or condition of the object.
Kinetic Energy
The energy of a moving object due to the object’s motion.
Mechanical Energy
The amount of work an object can do because of the object’s kinetic and potential energies.
Elastic Potential Energy
The energy stored in any type of stretched or compressed elastic material, such as a spring or bungee cord.
Gravitational Potential Energy
Depends both on the mass of the object’s in a system and on the distance between them.
Nonmechanical Energy
Energy that lies at the level of atoms and that does not affect motion on a large scale.
Efficiency
A quantity, usually expressed as a percentage, that measures the ratio of useful work output to work input.
Open System
Exchange energy with the space around them.
Closed System
When the flow of energy into and out of a system is small enough that it can be ignored.
Perpetual Motion Machine
A machine designed to keep on going forever without any input of energy.
