7P2: Energy
What is energy?
7P2: Energy
Energy stores
Complete the third column in the table on page 155 as we look at the different energy stores.
Thermal – The energy an object because it is warm.
All objects have this unless they are at absolute zero (-273 oC).
The hotter and the bigger an object is, the more energy it has.
This is the movement or vibrating of particles.
Kinetic - The energy objects because they are moving.
Big and fast objects have more kinetic energy than slow small objects.
Gravitational potential energy – the energy things have by being high up and large.
How worried you would be about it falling on your head? The more GPE it has the more worried you should be!
Chemical energy – the energy stored in things until they undergo chemical reactions.
Good examples would be fuels like petrol, cake that supplies energy to people, batteries and body fat which is where we store our energy until we need it.
Elastic potential energy – the energy of a stretched thing that could be released.
Magnetic potential energy – just like elastic except the ‘ping’ is caused by magnets attracting or repelling
Electrostatic
energy – the energy transferred in electrical circuits, lightning and static electricity.
Nuclear energy
It is the energy held in the nucleus of an atom, released in nuclear reactions.
1. Circle the events below where you think energy might possibly be being transferred
2. Pick at least three of the events that you have circled and suggest where the energy that allowed them to happen came from:
3. Suggest at least three different events to the ones above where energy is transferred
4. Describe some more events where energy is not being transferred.
Answer the questions
on page 154
Answer questions
1 & 2 on page 156
Answer questions
1 & 2 on page 156
The energy stored in moving objects | • |
| • | Chemical |
The energy stored in the nucleus of an atom | • |
| • | Gravitational |
The energy stored in chemical bonds | • |
| • | Kinetic |
The energy stored in objects that are high up | • |
| • | Thermal |
The energy stored in stretched objects | • |
| • | Nuclear |
The energy stored in warm objects | • |
| • | Elastic |
1. When I push the trolley, energy is transferred ...
from the ........................... store of ..........................
to the ........................... store of .......................... .
2. As the trolley rolls along the bench, energy is transferred ...
from the ........................... store of ..........................
to the ........................... store of .......................... .
Kinetic
Thermal
Chemical
Nuclear
Magnetic
Elastic
Gravitational
Electrostatic
3. When I let the load fall, energy is transferred ...
from the ........................... store of ..........................
to the ........................... store of .......................... .
Kinetic
Thermal
Chemical
Nuclear
Magnetic
Elastic
Gravitational
Electrostatic
4. When I pull the trolley back, energy is transferred ...
from the ........................... store of ..........................
to the ........................... store of .......................... .
5. When I let the trolley go, energy is transferred ...
from the ........................... store of ..........................
to the ........................... store of .......................... .
6. When I let go of the magnets, energy is transferred ...
from the ........................... store of ..........................
to the ........................... store of .......................... .
Kinetic
Thermal
Chemical
Nuclear
Magnetic
Elastic
Gravitational
Electrostatic
7. When I lift the pendulum up, energy is transferred ...
from the ........................... store of ..........................
to the ........................... store of .......................... .
8. When I let the pendulum go, energy is transferred ...
from the ........................... store of ..........................
to the ........................... store of .......................... .
9. When the pendulum swings back up, energy is transferred ...
from the ........................... store of ..........................
to the ........................... store of .......................... .
Kinetic
Thermal
Chemical
Nuclear
Magnetic
Elastic
Gravitational
Electrostatic
10. When I turn the circuit on, energy is transferred electrically ...
to the ........................... store of the ..........................
and this is transferred as electromagnetic waves of visible ........................... and infrared .......................... .
Kinetic
Thermal
Chemical
Nuclear
Magnetic
Elastic
Gravitational
Electrostatic
11. When I let the mass fall, energy is transferred ...
from the ........................... store of ..........................
to the ........................... store of .......................... .
12. When I let the mass bounce back up, energy is transferred ...
from the ........................... store of ..........................
to the ........................... store of .......................... .
Kinetic
Thermal
Chemical
Nuclear
Magnetic
Elastic
Gravitational
Electrostatic
14. When I add water to urea, energy is transferred ...
from the ........................... store of ..........................
to the ........................... store of .......................... .
13. When I add hydrochloric acid to magnesium , energy is transferred ...
from the ........................... store of ..........................
to the ........................... store of .......................... .
SAFETY SPECS ON
Kinetic
Thermal
Chemical
Nuclear
Magnetic
Elastic
Gravitational
Electrostatic
7B1 got to here
Answer questions
3 – 9 on pages 157 - 160
7P2: Energy
Conservation of Energy
Conservation of energy
Answer questions
1 & 2 on page 161 - 162
What transfers are happening as the pendulum swings back and forth?
Answer questions
1 & 2 on page 161 - 162
Sankey diagrams
Answer questions
3 & 4 on page 162 - 163
Answer questions
3 & 4 on page 162 - 163
7P2: Energy
Energy can be transferred in 4 ways
mechanically
electrically
heating by particles
by radiation
Complete the table on page 164 as we discuss these
Energy Stores and Pathways
By mechanical working
– a force causing a change in energy stores
Write at least one example of a mechanical transfer in the final column of the table on page 164
Energy Stores and Pathways
By electrical working
When an electrical current causes a change in energy stores
Write at least one example of an electrical transfer in the final column of the table on page 164
Energy Pathways
By heating (by particles)
Thermal energy transferred from hotter particles to colder ones or a transfer caused by a chemical reaction
Write at least one example of a heating transfer in the final column of the table on page 164
Energy Stores and Pathways
By radiation
radiation – energy transferred as a wave eg light, infrared, sound - the Sun emits light radiation and infrared radiation
Write at least one example of a radiation transfer in the final column of the table on page 164
Answer questions
1 to 10 on page 164 - 167
Extended writing task
Get into pairs with someone who you will work really well with.
Then, we’ll do this a bit at a time.
I will be marking your answer to this question.
∙ The changes in the forces acting on the ball
∙ The change in the ball's motion
∙ The forms of energy present
∙ The energy transfer process
∙ And conservation of energy.
You have 2 minutes to discuss the highlighted section of the answer.
Make notes on your whiteboard.
Then you will have a minute to write your answer in silence.
∙ The changes in the forces acting on the ball
∙ The change in the ball's motion
∙ The forms of energy present
∙ The energy transfer process
∙ And conservation of energy.
You have 2 minutes to discuss the highlighted section of the answer.
Make notes on your whiteboard.
Then you will have a minute to write your answer in silence.
∙ The changes in the forces acting on the ball
∙ The change in the ball's motion
∙ The forms of energy present
∙ The energy transfer process
∙ And conservation of energy.
You have 2 minutes to discuss the highlighted section of the answer.
Make notes on your whiteboard.
Then you will have a minute to write your answer in silence.
∙ The changes in the forces acting on the ball
∙ The change in the ball's motion
∙ The forms of energy present
∙ The energy transfer process
∙ And conservation of energy.
You have 2 minutes to discuss the highlighted section of the answer.
Make notes on your whiteboard.
Then you will have a minute to write your answer in silence.
∙ The changes in the forces acting on the ball
∙ The change in the ball's motion
∙ The forms of energy present
∙ The energy transfer process
∙ And conservation of energy.
You have 2 minutes to discuss the highlighted section of the answer.
Make notes on your whiteboard.
Then you will have a minute to write your answer in silence.
7P2: Energy
Whenever a force is moved through a distance, we say that work has been done.
The work done is equal to the amount of energy which has been transferred.
Work done is measured in joules.
Chris
Phil
ON whiteboards:
Who is doing the most work (transferring the most energy , Chris or Phil?
Can you say why?
He is moving the box a greater distance.
Chris
Phil
ON whiteboards:
Who is doing the most work (transferring the most energy , Cris or Phil?
Can you say why?
The box he is moving is bigger, so he has to use more force to move it
| Worked example | 7P2.4a Question for you to try |
H | How much energy is transferred when a 50 N force is applied to a wheelbarrow to push it 20 m down a garden? | A person lifts a hat 1.5 m from the floor onto their head. They apply a constant upwards force of 4 N to the hat to do this. How much extra energy is stored in the hat? |
E | | |
I | | |
S | | |
T | |
| Worked example | 7P2.4a Question for you to try |
H | A force of 600 N is used to move a rocket 120 m into the sky. How much energy is transferred? Give your answer in kJ. | To move a cart 300 m along a slope at a constant speed of 3 m/s a horse had to apply a force of 500 N. How many kilojoules of energy were transferred? |
E | | |
I | | |
S | | |
T | |
Answer the questions on page 171. When you have answered each question, check your answers against the correct answers in the box in the top left-hand corner.
Finally, answer the exam questions on pages 172 - 177.
Don’t forget the values have to be in the correct units – metres, newtons and joules.
Answer the questions on page 171.
Answer the exam questions on pages 172 - 177.