Chapter 12 Flashcards
Work
The transfer of energy to a body by the application of a 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 advantages
A quantity that measures how much a machine multiplies or energy or distance
Joule
Equivalent to 1kg*m^2/s^2
SI unit for work
Watt
SI unit for power
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
One family of simple machines. Hammer to pull out nail
First class lever
Have a fulcrum located between the points of application of the input and output forces(hammer)
Second class lever
The fulcrum is at one end of the arm and the input force is applied to the other end (wheelbarrow)
Third class lever
Multiply distance rather than force. They have a mechanic,a advantage of less than 1.(forearm)
Pulley
Another type of simple machine in the lever family.(raising a flag on a flag pole)
Block and tackle
Multiple pulleys put together in a single unit
Wheel and axle
Made of a lever or a pulley connected to a shaft. (Steering wheel)
Inclined plane
Second family of simple machines
Wedge
.two inclined planes back to back. (Axe blade)
Screw
Inclined plane wrapped around a cylinder.
Potential energy
The energy that an object has because of the position, shape, or condition of the object
Kinetic energy
The energy of a moving object due to the objects motion
Mechanical energy
The amount of work an object can do because of the objects kinetic and potential energies
Elastic potential energy
The energy stored in any type of stretched or compressed elastic material
Gravitational potential energy
The energy that could potentially do work on the apple. (Apple falling from tree because stem breaks off)
Nonmechanical energy
Energy that lies at the level of atoms and that does not effect 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 that surrounds them. (Earth-receives energy from sun and radiates some of its own energy out into space)
Closed system
When the flow of energy into and out of a system is small enough that it can be ignored
Perpetual motion machine
Machine designed to keep on going forever without any input of energy
