Transcript Potential and Kinetic Energy

Energy (NRG)
• (p 208) There are many forms of energy:
mechanical, thermal, electrical, nuclear
• One form of energy can be converted to
other forms
• When energy is changed to different
forms, work is done
Mechanical Energy
• Any time you store energy it gains the
potential to do work.
• Mechanical energy is the energy of an
object due to it position or motion.
• Mechanical NRG has two components
– Potential NRG – known as stored NRG
– Kinetic NRG – the energy of motion
Potential Energy
(p208) Potential energy is stored
energy due to position
Potential Energy (PE) can be stored
many ways:
a.
b.
c.
d.
e.
Gravitation: Ep=m×g×h or Ep = Fd
Elastic: Ep = ½ kx2
Chemical (batteries)
Thermal
Nuclear
Gravitational
Potential NRG
• This boulder has potential
energy due to position.
• It has the potential to crush
the student below.
• It also has the ability to do
work (by changing the
students shape)
Gravitational
Potential NRG
• When work is done against
gravity, this work is stored in
the system as: Gravitational
Potential Energy (GPE).
• GPE is dependent on:
– the force acting on the object
(Force of gravity)
• the vertical displacement of
the object (its height)
Gravitational Potential NRG
• (p 209) Gravitational
potential energy is always
measured relative to some
reference point
• Formula: Ep = mgh or Ep=Fd
• Unit: Joule (J) as Ep is a type
of work
• See example problems p 209
Kinetic NRG
• (p 212) Kinetic energy is
the energy of motion.
• When work is done
accelerating a object from
rest it becomes kinetic
energy.
• Kinetic energy formula:
Ek=½mv2
• Units: Joules (J)
• See example probs p 213