P1 - Conservation and Dissipation of Energy Flashcards
What is Energy measured in?
Joules (J)
Which systems can a thermodynamic system be in?
An open system
A closed system
An isolated system
How is energy tranferred between stores?
Through pathways
What are the 4 pathways where energy can be transfered?
Mechanically
Electrically
Be heating
By radiation
What does a mechanical pathway mean?
Energy transfer when a force acts on an object
What does an electrical pathway mean?
Energy transfer when a charge moves through a current
What does a ‘by heating’ pathway mean?
Energy transfer from a hotter object to an colder one
What does a ‘by radiation’ pathway mean?
Energy transfer by electromagnetic waves e.g. visible light
Where is Kinetic Energy store found?
In a moving object
Where Where is Chemical Energy store found?
Found in a fuel or battery
Where is Gravitational Potential Energy store found?
In an object above ground
Where is Elastic/ Strain Energy store found?
In a strethced or squashed object
Where is Thermal Energy store found?
In a substances temperature
Where is Magnetic Energy store found?
In two seperate magnets that attract or repel
Where is Nuclear Energy store found?
Radioactive decay
What are some examples of energy transfers through waves?
Light waves
Infra-red radiation (heat)
Sound waves
What is a Pendulum?
a body suspended from a fixed point so that it can swing back and forth under the influence of gravity
Explain the conservation of energy stores in a Pendulum.
As the Pendulum moves to the middle, G.P.E. is transferred ,by the force of gravity, to K.E.
G.P.E. decreases as the K.E. increases
As the Pendulum moves past the middle, K.E. Decreases and its G.P.E increases
This process is repeated
Why cant a Pendulum return to its initial starting height?
Due to air resistance, some energy is transferred to the surroundings
Therefore not all energy is transferred between the g.p.e. and k.e. Stores
What is The Law of The Conservation of Energy?
Energy cannot be created nor destroyed, only transferred from one form to another
What would a closed system look like in terms of a Pendulum experiment?
No energy is transferred out the Pendulum system so it WONT MOVE
What does ‘work’ mean in physics?
To move an object with an applied force
What is the equation for work done?
Work = force x distance
What is the equation for gravitational potential energy?
G.P.E = mass x gravitational field strengthx change in height
What is the equation for Kinetic Energy?
1/2 x mass x velocity°2
What is useful energy?
Energy that is transferred to where it is wanted and form it is wanted in
What is wasted energy?
Energy that is not usefully transferred
What is the equation for efficiency?
Efficiency = useful energy output / total energy supplied in X 100
What does it mean to ‘power a device’?
To supply a device with mechanical or electrical energy
What is ‘Power’ in physics?
The rate at which energy is transferred
What is Power measured in?
Watts, W
What does 1 Watt equal to?
1 Joule / s
What is the equation for power?
Power = energy / time
How do you calculate power wasted?
Power wasted = total power in - useful power out
microwave A has two times the amount of power of microwave B.
What does this mean?
Microwave A transfers energy two times faster than microwave B
What are two ways you could increase efficiency?
Add a lubricant to reduce friction and
Add a thermal insulator
to reduce thermal energy transfer to the surroundings
