Download PASS Review—Conservation of Energy Name: Energy can be in

PASS Review—Conservation of Energy
Name:
Energy can be in many forms:
Heat: transfer of thermal energy (motion of particles in a substance); the faster the particles move, the higher
the temperature. Burning materials, the Sun, and electricity have heat energy. Solar energy: from the Sun—
provides light and heat to Earth; solar cells convert solar energy to electrical energy; plants change solar
energy to chemical energy during photosynthesis; most of the energy on Earth comes from the Sun. Chemical
energy: stored in particles of matter; found in batteries or food/sugar. Electrical energy: flowing in an
electrical circuit. Anything with a wire will have electrical energy. Mechanical energy: due to motion and
position of an object; kinetic energy: energy of motion. Potential energy: stored energy.
The Law of Conservation Of Energy states that energy cannot be created or destroyed. It may be
transformed from one form into another, but the total amount of energy never changes. Potential to kinetic
transformation: water behind a dam starts moving; stretched rubber band is released; all forms of energy can
be changed to other forms: chemical energy in food is changed to mechanical energy for movement; plants
change solar energy in sun to chemical energy in sugar.
Magnetism is the force of attraction or repulsion of magnetic materials. A magnet is surrounded by a
magnetic field that applies a force without actually touching an object. An electric current flowing through a
wire wrapped around an iron core forms a magnet. A coil of wire spinning around a magnet or a magnet
spinning around a coil of wire can form an electric current.
Electromagnets: formed when a wire in an electric circuit is wrapped around an iron core producing a
magnetic field—if the current stops, the magnetism is lost. Generators: produces an electric current when a
coil of wire wrapped around an iron core is rotated near a magnet; Mechanical energy is changed to electrical
energy. Motors: convert electrical energy to mechanical energy; electromagnet rotates between the poles of a
magnet.
Electrical energy can be transformed to light, sound, heat, and mechanical motion in an electric circuit. A
circuit has a source of electrical energy, a wire, and a device to use the energy—must be connected in a
complete, unbroken path.
Energy is the ability to do work. In order for work to occur, a force must be applied to an object over a
distance, and the object must move in response to the force. If something has the ability to cause a change in
motion, it has energy. Energy is evident when work is being done. A spring scale measures force in units
called newtons.
A simple machine is a device that helps reduce the amount of force required to do work. Work is done when a
force is applied over a distance. Simple machines allow the user to apply a smaller force over a larger distance
to move an object; can also change the direction of the force. More distance = less effort. Levers: bar that
moves around a fulcrum; The closer the load is to the fulcrum, the easier it is to lift the load. Examples:
scissors, crowbar, tweezers, broom, wheelbarrow, bottle opener. Pulleys: grooved wheel with a rope; can
change the amount and/or direction of the force applied; single fixed pulley only changes the direction of the
force; the more ropes, the easier it is to lift; found on flag poles, window blinds, construction cranes. Inclined
planes: ramp; the longer the inclined plane, the easier it is to move the load. Examples: wheelchair ramps,
knives and nails (actually two planes put together=wedge); bolts and jar lids (plane wrapped around a
post=screw) Wheel and axle: two circular objects—central shaft (axle) inserted through middle of wheel;
found as door knobs, steering wheels, screwdrivers, gears, and bicycle wheels. Complex
machines/Compound machines—two or more simple machines working together. Examples: scissors
(levers and wedges); fishing pole (lever, wheel and axle, and pulley), and bicycle (numerous).