Chapter 12 Flashcards
Work
The transfer of energy to an object by the application of a force that makes the object move in the direction of the force.
Power
A quantity that measures the speed at which work is done.
Mechanical Advantage
A quantity that measures the amount a machine multiples force force or distance.
Joule
The unit used to calculate work. Joule is equivalent you 1 kgXm^2/s^2.
Watt
The unit used to measure power.
Simple machines
One of the six basic types of machines, which are the basis for all other forms of machines.
Compound machine
A machine which is made of more than one simple machine.
Lever
An example of a lever is a hammer pulling out a nail. The force applied to the hammer is transferred to the claw on the other end of the hammer.
First class lever
All first class levers have a fulcrum located between the points of application of the input and output forces
Second class lever
The fulcrum is at one end of the arm and the input force is applied to the other end. The wheel of a wheelbarrow is a fulcrum.
Third class levers
Third class levers multiply distance rather than force. As a result, they have a mechanical advantage of less than 1.
Pulley
A pulley is another type of simple machine in the lever family.
Block and tackle
Multiple pulleys that are sometimes put together in a single unit
Wheel and axle
A wheel and axle is made of a lever or a pulley connected to the shaft.
Inclined plane
An inclined plane turns a small input force into a large output force by spreading the work out over a large distance.
Wedge
A wedge turns a downward force into two forces directed out to the sides.A wedge acts like two inclined planes back to back.
Screw
A screw is an inclined plane wrapped around a cylinder.
Potential energy
The energy of an object has because of the position, shape, or condition of the object.
Kinetic energy
The energy of a moving object because of 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 is stretched or compressed elastic material, such as a spring or bungee cord.
Gravitational potential energy
Any system of two or more object’s separated by a distance contains gravitational potential energy resulting from the gravitational attraction between the objects.
Non mechanical energy
Energy that lies at the level of atoms and that doesn’t affect motion on a large scale
Efficiency
A quantity that is mostly expressed as a percentage, and measures the ratio of useful work output to work input.
Open system
Systems that exchange energy with the space that surrounds them
Perpetual motion machines
A machine that is designed to go on forever without any input of energy.
Closed systems
When the flow of energy into and out of a system is small enough that it can be ignored
