Energy part 1 Flashcards
What is a system ?
A system is an object or a group of objects .
What do systems have ?
What is energy measured in?
Systems have energy .
Energy is measured In Joules.
What cannot happen to energy ?what can happen to energy ?
Energy can not be created or used up or destroyed.
Energy can only be stored or transferred.
Where is energy stored ?
When is energy transferred ?
Energy is stored in different
energy stores .
Energy is transferred when a system changes .
What is the amount of energy transferred called ?
The amount of energy transferred is called “work done”
What is the most common misunderstanding about energy ?
There aren’t different types of energy, just different ways of storing it.
What are examples of different energy stores ?
7 examples
Energy can be found in different stores: chemical, elastic potential, electrostatic, gravitational potential, kinetic, magnetic, nuclear
Where do all objects have energy ?
What does this not apply to ?
All objects have energy in their thermal energy store (unless they are at a temperature of absolute zero).
How can objects have more energy in their thermal energy store ?
Objects have more energy in their thermal energy store when their temperature rises.
How can Objects have energy in their gravitational potential energy store?
Objects raised against the pull of gravity have energy in their gravitational potential energy store.
How can objects have chemical energy store?
Where do moving objects have energy in ?
Objects with chemical bonds have energy in their chemical energy store.
Moving objects have energy in their kinetic energy store
How can you have elastic potential energy?
Objects being stretched or squashed have energy in their elastic potential energy store.
How can you have energy in magnetic energy store?
When magnetic materials attract or repel each other they have energy in their magnetic energy store
How can you have electrostatic energy store ?
When charged particles attract or repel each other they have energy in their electrostatic energy store
How can you have nuclear energy store?
Atomic nuclei have energy in their nuclear energy store.
What happens when a system changes in witch direction ?
When a system changes energy is transferred.
Energy may be transferred in different directions.
3 main ways energy can be transferred .
1) Energy can be transferred into or out of a system.
2) Energy can be transferred between different objects in a system.
3) Energy can also be transferred between different energy stores.
What happens when a person throws a ball upwards ?
For example, when a person throws a ball upwards their arm is doing work.
👉When a person throws a ball upwards how is energy being transferred ?
First, energy is transferred from their arm’s chemical energy store to their arm’s kinetic energy store.
👉Then how is the energy transferred ?
Then energy is transferred from the arm’s kinetic energy store to the ball’s kinetic energy store.
Then what happens as the ball moves upwards?
As the ball moves upwards, it slows down under the downwards force of gravity.
So what happens to the energy as the ball is moving upwards ?
So, energy is transferred from its kinetic energy store to its gravitational potential energy store.
What happens at the balls highest point ?
At its highest point it stops for a moment, this is the point all the energy has been transferred to the gravitational potential store.
What happens to the energy as the ball falls ?
As it falls again, the energy from the gravitational potential store is transferred back to the kinetic store.
What is the equation for kinetic energy ?
In words and formula
1 2
E = — mv
2
1 2 Kinetic energy = —— x mass x speed (J) 2
How can an object have more Kinetic energy ?
Heavier, faster objects have more kinetic energy than lighter, slower objects.
What is the equation for elastic potential energy ?
1 2
E =— ke
2
1 Elastic potential energy(J) = — x spring
2 constant (N/m) x extension (m)
What is the spring extension ?
The spring’s extension is the difference between its stretched length and its original length.
What does the spring constant tell you ?
The spring constant tells you how difficult it is to stretch the spring.
What happens the more a string is stretched ?
The more a spring is stretched, the more elastic potential energy it stores.
When does the elastic potential energy equation work ?
This equation only works if the limit of proportionality has not been exceeded
What is the limit of proportionality ?
This is the point at which the spring’s extension is no longer proportional to the force stretching it.
What does stretched springs store ?
Stretched springs store elastic potential energy
What does an objects kinetic energy depend on ?
The amount of energy in an object’s kinetic energy store depends on its mass and speed
Where is energy transferred ?
Energy can be transferred in different directions
What energy stores do objects have ?
Where is energy stored ?
Objects have different energy stores.
Energy is stored in a system.
What is the equation for gravitational potential energy ?
E=m x g x h
Gpe=mass(kg) x gravitation field strength (N/Kg)x height(m)
What does gravitation field strength depend on ?
Gravitational field strength depends on the mass of the planet the object is on.
What is the gravitational field strength on earth ?
On Earth, the gravitational field strength is 9.8 N/kg.
What does this mean calculations for objects on earth will be ?
This means calculations for objects on Earth will always use 9.8 N/kg.
How can an object gain more gravitational potential energy ?
The higher an object is above ground level, the more gravitational potential energy it stores.
