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Energy, Work, and Power
By: Boniquit, Ross Mignonette
&
Tan, Bernadette B.
ACS2A
Energy
• Ancient Greek: energeia
meaning "activity, operation"
• Is the Ability to Do Work.
• SI unit of energy = joule (J)
• Energy = Power x Time
Nature of Energy
• Energy is all around you!
– You can hear energy as sound.
– You can see energy as light.
– And you can feel it as wind.
Nature of Energy
• You use energy when you:
– hit a softball.
– lift your book bag.
Nature of Energy
• Energy is involved when:
– a bird flies.
– a bomb explodes.
– rain falls from the sky.
– electricity flows in a wire.
Types of Energy
• Kinetic Energy
– Energy of motion.
– The faster an object moves and the
greater the mass of a moving object, the
more kinetic energy it has.
– Examples:
• Ball dropping
• Electricity
• Potential Energy
– Stored energy.
– Examples:
• Pulling back on a bow’s arrow.
• Lifting a heavy ball high in the air.
Forms of Energy
• The five main forms of energy are:
– Heat or Thermal Energy
• the vibration and movement of the atoms
and molecules within substances.
– Chemical Energy
• energy stored in the bonds of atoms and
molecules.
– Electrical Energy
• delivered by tiny charged particles called
electrons, typically moving through a wire.
– Nuclear Energy
• energy stored in the nucleus of an atom —
the energy that holds the nucleus together.
– Mechanical Energy
• energy stored in objects by tension.
Work
•
•
•
•
•
The transfer of energy through motion.
Using a force to move an object.
Unit of work = joule (J)
Work = Force x Distance
Examples:
• A person lift a box to a height of 1m with
5N of force, he is doing some work and his
work is 5N.
Simple Machines
• A machine is a device that helps make work
easier to perform by accomplishing one or
more of the following functions:
• transferring a force from one place to
another,
• changing the direction of a force,
• increasing the magnitude of a force, or
• increasing the distance or speed of a force.
• Levers help us lift weights with less effort.
• For example: scissors, can opener, fork,
stapler
• Makes it easier to slide a load upward than to
lift it directly.
• For example: a ramp may be used when
loading or unloading heavy objects out of a
delivery truck.
• A wedge is closely related to the inclined
plane. A wedge can be used to lift a heavy
load over a short distance or to split things
into two pieces.
• For example: knife, shovel
• A screw is simply an inclined plane that is
wrapped around a cylinder or a cone. The
main purpose is to raise a load over the
threads, which is the spiral part of the screw,
by applying a small force.
• A pulley changes the direction of a force and
uses grooved wheels and a rope to raise,
lower or move a load.
• For example: flagpole
Power
• Rate of doing work
• Unit of power = watt (W)
• Power = Work / Time
Types of Power
• Electrical Power
• Uses electrical energy to do work.
• Mechanical Power
• Uses mechanical energy to do work.
• Fluid Power
• Uses energy transferred by liquids and
gases.