Unit 7I Energy resources Lesson 6

Energy resources lesson plans

Lesson 6 energy and food

Aim – Where does all our energy originate from?

5 minutes Starter Students have previously studied food chains. Ask them what normally starts any food chain? Why do we have to have a plant at the start? Where do plants get their energy from?

20 minutes Trace the food chain ending in a glass of milk back to its source – the sun. The energy in the foods we eat can be traced through a food chain with the Sun’s energy at the start of the chain.

Similarly, trace the energy of a moving car or bus back to the sun – fossil fuels were living organisms that transformed and stored the suns energy.

Students answer Q 1 and 2 p.107

30 minutes Use p 107 as stimulus material for a discussion on how we can use energy well.
Pupils may wish to present the points that arise in the form of display material or a debate.

National curriculum links: Sc4 5a/b/c energy resources

Grading:

Level 5 Describe the type of energy that an object has or is using

Level 6 Describe how energy is transferred from the Sun to other energy resources

P2 Unit 5 5.2 Resistance & 5.3 current potential difference graphs

Additional Science P2 Unit 5: Current electricity.

Lesson 2: Resistance & current-potential difference graphs

Textbook section P2 5.2 & 5.3

Aim: How do wires, filament lamps, diodes, LDR’s & thermistors affect the resistance in an electrical circuit?

Starter (10 min):
Students recap last lesson by answering summary questions 1 & 2 on pg 237 of the textbook. Mr C will provide the answers and students should self assess their work.

Main Activity 1 (20 min): Current/Potential difference graphs for wires, filament lamps and diodes.

Students are given some data and have to draw a current/potential difference graph for the above components. Mr C will provide the data but students can use their own data for wires and filament lamps if they completed the experiment from last lesson. Students should note the shape of the graphs.

Provided the temperature is kept constant the resistance of a wire is always the same. Because R = V/I the resistance (slope of the graph) is always a straight line through the origin of the graph.
The current-potential difference graph for a filament lamp curves. So the current is not directly proportional to the potential difference. Resistance in a filament lamp increases as the filament lamp heats up, so resistance increases when current increases. Reversing the direction of the current makes no difference to the shape of the graph.
The current through a diode flows in one direction only. In the reverse direction the diode has a very high resistance so the current is virtually zero.

Main Activity 2 (20 min): Thermistors and LDR’s

Mr C will describe how Thermistors and Light dependent resistors affect electrical circuits using Virtual Physics Laboratory.
Students then have to match the five components discussed today to descriptions of their effects on electrical circuits.

http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa/electricity/resistancerev3.shtml more information from BBC Bytesize.

Plenary (5 min): Four key questions

From Physics revision cards.

AQA Specification: Unit Physics 2.13.6

P2 2.5 Falling objects

Lesson 4: Falling objects

Textbook section P2 2.5

Aim: How does a parachute work?

Starter (10 min): F=ma becomes weight (N) = mass (kg) x acceleration due to gravity (m/s2)
When objects fall freely, the resultant force acting on them is the Earth’s force provided by Earth’s gravitational field. This will make an object accelerate at about 10 ms2 close to the Earth’s surface.

We call the force of gravity ‘weight’ and the acceleration ‘the acceleration due to gravity’.

F=ma becomes weight = mass x gravitational field strength.

When objects fall through fluids (such as water and air), the fluid exerts frictional forces on the object. > the velocity of the object then > frictional force. Eventually the two forces (weight & friction) will balance, resultant force = zero and the object moves at a steady velocity. This is called the ‘terminal velocity’. Possibly show the ball bearing in air, water, and honey demonstration.

http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa/forces/forcemassrev4.shtml see BBC Bytesize for more on this topic.

Main activity (30 min): Egg parachute competition.

Students have to think about what makes a good parachute (one that creates the most drag force/air resistance so > deceleration, <> time taken to hit the ground). They have 15 min to build an egg parachute which will then be tested outside (materials plastic bags, string, tape, 1 egg per team).
Rules
1. No cushioning for the egg
2. If the egg breaks you are disqualified
3. The team whose parachute took the longest to hit the ground without the egg breaking are the winners. The winning team will receive a prize.

Plenary (15 min):

Students are given a velocity time graph for a falling object, they have to describe what is happening at each stage using the key words and terms. They should also calculate the size of the forces using the equation w = m x g.
Accelerates, Weight, Gravity, Drag force, Increase, Decrease, Terminal velocity, greater than, equal to

AQA Specification – Physics 2.13.2
· The faster a body moves through a fluid the greater the frictional force that acts on it.
· A body falling through a fluid will initially accelerate due to the force of gravity. Eventually the resultant force on the body will be zero and it will fall at its terminal velocity.
· Calculate the weight of a body using: weight (newton, N) = mass (kilogram, kg) x gravitational field strength (newton/kilogram, N/kg)Draw and interpret velocity-time graphs for bodies that reach terminal velocity, including a consideration of the forces acting on the body.

P2 Unit 2.4 On the road

Lesson 3: On the road

Textbook section P2 2.4

Aim: What factors affect the stopping distance of vehicle on the road?

Starter 10 min: 10 key questions that provide a recap of the previous two lessons. These should be attempted without books. Mr C will provide the answers and students should self assess their work.

Main activity 30 min:
When a vehicle is travelling at a steady speed the resultant force acting on it is zero, so driving forces are equal & opposite to frictional forces.
The braking force needed to stop that vehicle depends on the velocity and mass of the vehicle. > velocity and/or > mass = > braking force.
The total stopping distance of a vehicle is the distance it travels during the driver’s reaction time (the thinking distance) plus the distance it travels under the braking force (the braking distance).
Stopping distance = thinking distance + braking distance. With the same driver and car the thinking & braking distance will increase when the initial velocity increases.
The thinking distance will increase if the driver is tired or under the influence.
The braking distance can be increased by poorly maintained roads, bad weather conditions & the condition of the car i.e. worn brakes or tyres.

Students have to...
1. Use the textbook to draw a diagram or series of diagrams that summarise the above, it should be simple and concise and include as many key points as possible. To help them begin a diagram of Mr Average in his average car is shown on the board.
What is a stopping distance? Explained by Mr Average.
What factors affect braking force?
What factors affect the thinking distance and braking distance?
2. Complete summary questions 1 & 2 on pg 203 of the text book. Mr C will provide answers at the end of the lesson.
3. If there is time the lesson can be finished with some reaction tests using software on the computer.

http://www.gcse.com/fm/stopping_distances.htm a good summary of the material covered in this lesson.

Plenary (10 min)...
Students can try some practice exam questions. Mr C will give the answers and students should mark and correct their own work.

AQA Specification – Physics 2.13.2
· When a vehicle travels at a steady speed the frictional forces balance the driving forces.
· The greater the speed of a vehicle the greater the braking force needed to stop it in a certain distance.
· The stopping distance of a vehicle depends on the distance the vehicle travels during the drivers reaction time and the distance it travels under the braking force.
· A driver’s reaction time can be affected by tiredness, drugs and alcohol.
· A vehicle’s braking distance can be affected by adverse road and weather conditions and poor condition of the vehicle.

P2 Unit 5 lesson 1 Resistance & p.d/current graphs

Resistance & current/voltage graphsLesson P2 5.1/2/3

Aim: Calculate resistance (ohms) and draw current/p.d graphs for a wire, filament lamp and a diode.
Key words: Potential difference, resistance, voltage (p.d), current, filament lamp, diode.

Starter: Recap of circuits and introduction to Resistance equation...
Resistance (ohms) = Potential difference (Volts)/current (amperes).
R = V/I. Students try some examples to practice using the equation.

Main: Mr C will introduce current/p.d graphs and quickly demonstrate the circuit that you will need to set up. You will be changing the voltage in the circuit and measuring the effect this has on the current using an ammeter. You will then need to record your results in a table and plot them on a graph. The slope of the line represents the resistance in the circuit. Make sure you investigate the effect that wires, filament lamps and diodes have on resistance.
Write a short conclusion that summarises your observations. How do the various appliances effect resistance in electrical circuits (the slope of the graph).

Plenary: Mr C will go over what you should have observed during the experiment. Make sure you assess your own work so you know your understanding is correct.
To end the lesson Mr C will explain how thermistor’s and LDR’s (Light dependent resistors) affect resistance in a circuit. If there is time the summary questions on pg 239 of the textbook can be attempted.

Homework: from H/W book.

AQA Specification Link up
Physics 2.13.6

Unit 7I Lesson 5 Energy and food

Energy resources lesson plans

Lesson 5 energy and food

Aim – Calculate the energy content of two different brands of crisp

5 minutes – recap of the last two lessons about renewable energy and fossil fuels.

This lesson is has two parts – In the first part discuss and identify our energy related need for food. In the second part is an experiment.

10 minutes Starter Living things such as people transform the energy provided by food into other forms
We need heat to maintain our body temperature. Energy from food is transformed into movement including the movement needed to make our lungs breath air and our heart pump blood. The food we eat combines with oxygen to make the energy.

If we eat more than we need the food is converted into fat.

You need to remember that humans convert the chemical energy from food into movement (kinetic) energy and heat energy.

Some types of food provide more energy than others. The energy content of food can be measured in units called Joules. If you throw an apple about 1 metre into the air then you use up about 1 Joule of energy.

30 minutes Main activity and experiment

Comparing the energy content of two different types of crisp

Measure out 10 ml of water and pour it into a boiling tube.
Carefully place the tube in a clamp stand.
Use a thermometer to record the starting temperature of the water.
Carefully light the crisp using a Bunsen burner and hold underneath the boiling tube.
Once the crisp has extinguished record the finishing temperature of the water.

The specific heat capacity of water is approximately 0.42 Joules/g. We can work out the energy content of each crisp by using the equation…

Energy content = temperature change of water x 42 (10 grams of water)

Megan and Georgina's energy content = 19 x 42 = 798

Energy content of 100g of crisps = Energy content/mass of wotsits x 100.

Megan and Georgina's energy content of crisps = 798 Joules / 1.5 grams x 100 = 53,200 Joules

Do our results agree with what the food labels on the crisps say?

According to the label a 100g of Wotsits contain 2,270,000 Joules.

What!?! So where did all the energy go? Thats what we will be finding out in the next unit 'Heating and Cooling'.

Grading

Level 4
List the eight forms of energy

Level 5
Describe some energy transfers including some which involve living things

National curriculum links

Sc4 5a Energy resources

Sc1.2g- observations

F5

I've been experimenting with getting photos online as I'd like (subject to permission) to put some photos of Science club and other fun experiments onto the blog.

This photo cropped up, it is from a Physics course I attended that involved making Rockets that were launched using a compressed air rig. The rocket is named dually after the legendary 'Mr Fish' and Brock Lesnar's finishing move of the same name.

The rocket flew the third furthest distance in a competition between about 20 other Physics teachers. The winner was built by a graduate astro physicist - that's what studying environmental scientist will do for you!