Page 1 Work & Energy Discussion Definition Dot Product Work of a constant force Work/kinetic energy theorem Work of multiple constant forces Comments SPH3U: Introduction to Work and Energy Work & Energy One of the most important concepts in physics Alternative approach to mechanics Many applications beyond mechanics Thermodynamics (movement of heat) Quantum mechanics... Very useful tools You will learn new (sometimes much easier) ways to solve problems Energy is.. • The ability to do work • Measured in Joules • We use energy to do whatever task we need to do (move a car, lift a pencil, etc) Types of Energy Energy can come in many forms including: – Thermal (energy in the form of moving atoms) – Electrical (energy possessed by charged particles) – Radiant (energy found in EM waves) – Nuclear (energy stored in holding the atom together) – Gravitational (energy stored due to a raised elevation) Types of Energy cont. – Kinetic (energy due to motion of objects) – Elastic (energy stored in compression or stretch) – Sound (energy in vibrations) – Chemical (energy stored in molecular bonds) Energy 101 Energy cannot be created or destroyed, it can only transform from one form to another. • Eg. A student turns on the stove to heat a pot of water Electrical Radiant Thermal
7
Embed
Energy is.. Types of Energy - Michael Burnsmjburns.net/SPH3U/Energy/1-Introduction to Work.pdf · Work & Energy Discussion Definition Dot Product Work of a constant force ... SPH3U:
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Page 1
Work & Energy
Discussion
Definition
Dot Product
Work of a constant force
Work/kinetic energy theorem
Work of multiple constant forces
Comments
SPH3U:
Introduction to Work and Energy
Work & Energy
One of the most important concepts in physics
Alternative approach to mechanics
Many applications beyond mechanics
Thermodynamics (movement of heat)
Quantum mechanics...
Very useful tools
You will learn new (sometimes much easier) ways to
solve problems
Energy is..
• The ability to do work
• Measured in Joules
• We use energy to do
whatever task we
need to do (move a
car, lift a pencil, etc)
Types of Energy
Energy can come in many forms including:
– Thermal (energy in the form of moving atoms)
– Electrical (energy possessed by charged particles)
– Radiant (energy found in EM waves)
– Nuclear (energy stored in holding the atom together)
– Gravitational (energy stored due to a raised elevation)
Types of Energy cont.
– Kinetic (energy due to motion of objects)
– Elastic (energy stored in compression or stretch)
– Sound (energy in vibrations)
– Chemical (energy stored in molecular bonds)
Energy 101
Energy cannot be created or destroyed, it can
only transform from one form to another.
• Eg. A student turns on the stove to heat a pot
of water
Electrical Radiant Thermal
Page 2
Energy and Work
• We know energy is the ability to do work, but
what is work?
• In physics work is the energy transferred to an
object by an applied force over a displacement
Forms of Energy
Kinetic: Energy of motion.
A car on the highway has kinetic energy.
We have to remove this energy to stop it.
The brakes of a car get HOT!
This is an example of turning one form of energy into
another (thermal energy).
21
2K mv
Mass = Energy
Particle Physics:
+ 5,000,000,000 V
e-
- 5,000,000,000 V
e+ (a)
(b)
(c)
E = 1010 eV
M E = MC2
( poof ! )
Energy Conservation
Energy cannot be destroyed or created.
Just changed from one form to another.
We say energy is conserved!
True for any closed system.
i.e. when we put on the brakes, the kinetic energy of the car is turned into heat using friction in the brakes. The total energy of the “car-brakes-road-atmosphere” system is the same.
The energy of the car “alone” is not conserved...
It is reduced by the braking.
Doing “work” on an isolated system will change its “energy”...
Work
• Mechanical work is done on an object when a force displaces an
object.
• Note that this equation only applies when the force is constant and
the force and displacement are in the same direction.
• When the force and displacement are not entirely in the same
direction, the component of the force in the direction of the