LESSON B:BLENDED TECHNIQUE GROUP

YOUR OBJECTIVE IS TO FIND ANSWERS TO THESE QUESTIONS1. What is energy? Work? Give A definition..2. What is Potential Energy? Show at least TWO practical examples in

which we can identify it Where is ENERGY? Which forms does it assume?3. What is Kinetic energy? Where do you find it? 4. Energy in everybody life: which forms of energy do you know now?

Recognize them in given situations (SOME EXAMPLES, SITUATIONS ETC..)

5. Transformations. How energy changes its form. Describe some transformations in the given examples. Give some examples of your own experience.

6. Which is the very important property of energy? ( Even if energy changes its forms, it is always ...)

7. Energy and sports: which kind of energy do you find in sports? give examples,

8. what about you? Which sport do you practice, if one? Which forms of energy do you find in your sport?

9. Food and energy: compare different activities and choose the more energy expensive one

10.How many calories do you need to ...... (run at .., walk to the top of a mountain.. etc..) read and understand some tables of comparison.

11.Units of measure: equivalences between different units (metres and kilometres, Joules and Calories, km/h, m/s, mph)

12.Solve some exercises: compute how much Kinetic or potential energy there is in a certain situation. Ho many calories you consume during a given activity.

● YOU MIGHT FEEL UNSAFE AT DOING IT ALONE, SO YOUR TEACHERS HAVE ALREADY PREPARED SOME HINTS AND IDEAS, TO HELP YOU LEARNING THESE TOPICS

● WORKING IN GROUPS IS FUNDAMENTAL BOTH TO FIND AND GIVE HELP

● USE ANY KIND OF RESOURCES YOU LIKE CHOOSING IN THE LISTS GIVEN BELOW.

● ANYBODY OF YOU WILL BE ASKED TO ANSWER ALL THE QUESTIONS OF THE LIST

● ALL OF YOU WILL DO A TEST ON THE TOPIC (FRIDAY)

REMEMBER!! BE AWARE OF YOUR FEELINGS AND THOUGHTS DURING THE LESSON, SINCE YOU WILL BE ASKED TO TELL US YOUR OPINION BY FILLING A SURVEY ON TEACHING METHODOLOGY.

GUIDED LESSON : here are given some suggested sources for each topic.

WEBSITES, VIDEOS www.dictionary.com/browse/energy

https://en.wikipedia.org/wiki/Energy

www.softschools.com › Examples › Science Examples OF ENERGY transformations

https://quizlet.com/129911315/energy-transformations-and-examples-flash-cards/ with some guided exercises

https://youtu.be/PD7a1EWjsTc (5:53)

https://youtu.be/IqV5L66EP2E (4:38) https://youtu.be/T5WJoup-RD8 (3:44)https://youtu.be/z8a-L1lkq3w (5:46)https://youtu.be/-8atIc3XixY (5:59)https://youtu.be/x9heJMbz_kk (2:45) some exercise to fillhttps://youtu.be/i6e-KrNCe_E (3:11)https://youtu.be/f8_n5QAkTmg (2:36) very guidedhttps://youtu.be/IipOCx2cB-A (1:15) pure fun and impressive

transformations!!

SIMULATIONS TO UNDERSTAND PHYSICSGo to the website: https://phet.colorado.edu/

Digit : energy in the search slit (with the mignifying glass ) Check the useful simulations:https://phet.colorado.edu/en/simulation/legacy/energy-forms-and-changeshttps://phet.colorado.edu/en/simulation/legacy/energy-skate-park-basicshttps://phet.colorado.edu/sims/energy-forms-and-changes/energy-forms-and-changes_en.jnlp

IMAGES AND TABLES

.

TEXTS

Energy TransformationsAn energy transformation is the change of energy from one form to another. Energy transformations occur everywhere every second of the day.Energy Transformations Examples1. A toaster transforms electrical energy into thermal energy.2. A blender transforms electrical energy into mechanical energy.

3. The sun transforms nuclear energy into ultraviolet, infrared, and gamma energy all forms of electromagnetic energy.

4. Our bodies convert chemical energy from food into mechanical and electrical energy to allow us to move.

5. A natural gas stove converts chemical energy from burning into thermal energy used to cook food.

Some other exemples will help us understand another bit of our nature. Electrical Energy to Thermal Energy ConversionsElectrical energy is a form of energy that occurs as a result of either stored or moving charged particles. When the energy is stored it is called electric potential energy and when it is moving in an electric current it is a form of kinetic energy. Our most common form of electrical energy is found in our wall outlets. Thermal energy is energy that results from moving atoms or molecules and is commonly referred to as heat. The faster the atoms or molecules move, the more heat or thermal energy they have. In these examples we will be exploring instances where electrical energy is converted into thermal energy for use.Examples of Electrical Energy to Thermal Energy Conversions:1. A toaster draws electric current (electrical energy) from a wall outlet and converts these moving electric charges into heat (thermal energy) in the filaments that turn red hot to cook your toast.2. An electric clothes dryer turns electrical energy from a wall outlet into heat (thermal energy) to dry your clothes as they spin.3. A hair straightener turns the electrical energy from a wall outlet into heat (thermal energy).

4. As electricity runs through the filaments in a space heater, the electrical energy is converted into heat (thermal energy).

5. An electric stove plugged into a wall outlet uses the electrical energy to flow into the burners on the stove top and as the electric charges pass through the burners the electrical energy is converted into thermal energy.6. Although used for light, an incandescent light bulb produces mostly thermal energy (they get very hot) as it turns electrical energy into light by passing the electric charges through a very tiny filament.

And more...Chemical Energy Transformations to Thermal EnergyChemical energy is a potential form of energy that is stored in the chemical bonds that hold atoms together. If bonds are broken, the energy is released, and if bonds are formed, energy is absorbed. Thermal energy is often referred to as heat energy. As molecules move faster and gain kinetic or moving energy, the temperature of the substance increases. During conversions from chemical energy to thermal energy, the energy stored in the chemical bonds are released and this energy causes surrounding molecules to move faster thus increasing the thermal energy of a substance.Examples of Chemical Energy to Thermal Energy:

1. Coal is burned at a power plant. The chemical energy released as the coal is burned heats water and turns it into steam. The chemical energy causes the liquid water molecules to move faster increasing their thermal energy.2. Gasoline is burned in a car engine. As the gas burns, small explosions release heat or thermal energy which makes the pistons move so the car go.3. A furnace burns natural gas in a chemical reaction. As the natural gas burns, heat is released causing air molecules to move faster. The temperature of the air increases because they have more thermal energy which is used to heat a house.

4. Hand warmers used for hunting operate by chemical reaction. When the contents of the bag are mixed together, a chemical reaction causes chemical bonds to break releasing energy. This energy causes the thermal energy of the solution inside the bag to increase and we feel heat to warm our hands.

5. A butane torch burns butane gas. As the chemical bonds are broken during the reaction, heat is released. The heat is used to increase the thermal energy of a metal which melts and is used to weld pipes together.

EXERCISES : Here are some exercises to prepare your final test.

Some of them are completely solved, others are for your training.Solutions are provided at the end.

Have fun!1. sometimes we need to convert km/h in m/s speed, since the formula for kinetic energy wants

only metres and seconds. How can we do that?

DATA:

V= 30 km/hWe want it in m/s. The technique is:

Quite easy, isn’t it? we simply trasform km in metres, and hours in seconds and divide the result:

There is a very simple way to solve the riddle: can you guess it? Try by yourself and check it the note1

2. a car is running at a speed of 30.0 m/s. its mass is 1,200 kg (1.2 tons). Therefore its .................. ... energy is .........................................

DATA:v= 30.0 m/s is the speed

m= 1,200 km (one thousand two hundreds of course!) is the massThe only form of energy we can try to compute is kinetic energy

Therefore, we use the formula Ke = = 0.5*1200kg*(30 m/s)2 == 540 000 = 5.4*105 J

Therefore its KINETIC ... energy is = 5.4*105 JRemember the final measure unit J, and write the number in scientific notation.

The power (30 m/s)2 is to be computed before the multiplication.

. Now compute the kinetic energy for a dog (4.5 kg) running at 5 m/s, a Boeing 747 airplane (333 390 kg) flying at the speed of 800 km/h, a horse (450 kg) galopping at 65 km/h.3. from the table below, we find some bike racers speeds.

Transform the following speeds from mph (miles per hour) to km/hV1 = 10 mph = ........

V2 = 12 mph = .......V3 = 16 mph = .........

V4 = 25 mph = ...............

DATA:

1 To transform from km/h to m/s just DIVIDE BY 3.6! to tranform from m/s to km/h just MULTIPLY BY 3.6!

V = 10 mph speedRemember that 1 mile = 1,61 km,

Therefore we can solve an easy proportion1 mile/h : 1,61 km/h = 10 miles/h : X km/h

X km/h = 1,61 km/h *( 10 miles/h )/ 1 mile/h =16,1 km/hIt is very simple! Just multiply your speed by 1,61!

Some bikers are very quick, aren’t they?

4. Now let us know how to compute potential gravitational energy. Remember : it is fundamental for electricity production AND FOR SKIING AS WELL! . A cat is climbing a tree. The tree is 5.0 m tall, and the cat weights 1.5 kg.

Therefore his .................. ... energy is .........................................

DATA:

m= 1.5 kg cat’s massh=5.0 m final position

This energy is simply U= m*g*h = 1.5 kg*9.8 N/kg*5.0 m = 73.5 JWe use the number g=9.8 N/kg as the gravitational acceleration. It depends on the planet. On the Moon, it is very low, about 1.6 N/kg. It means that you would jump higher than an olimpic champion!!.

Which formula is used on another planet? Try to guess the answer and then check at the note2.

. Tom is on the top of a ski run, 1.5 km high. Tom is 85 km heavy . find his potential energy. When at the end of the run, how much maximum kinetic energy could he have?

DATA:m= 85 kg

h=1.5 km = 1.5 *103 mTo find the potential energy U= m*g*h = 85 kg*9.8 N/kg*1.5 *103 m= 1.25 * 10 6 J.

Lot of energy!How much kinetic energy?

If there is nothing to desturb his motion, his energy is preserved according to the principle of energy conservation, therefore he should have the same amount of energy. Yet lot of it gets lost due to frictions, air and snow interactions....

5. Computing calories.

Look at the tables below and ask yourself how much energy an athlete is consuming during his performances.

. a tennis complete game lasts a variable time but some computations give an average time of 2 hours and half . how many calories do the players consume?

2 . WHICH POTENTIAL ENERGY ON OTHER PLANETS? The same formula, OF COURSE, but with a different constant g!

DATA:C= 6.35 Calories /minute

T=2 hours and half = 2h*60 minutes/hour+30 minutes = 150 minutesLet us multiply our data

Total amount of energy = C*T = 6.35 Cal/min*150 min = 950 Calories= kilocaloriesIt seems not to much, but remember they are GREAT CALORIES,

1 Cal = 1 k cal (kilo calorie= 4 186 J! )So, 950 Cal = 4*106 J 4 millions of Joules! Quite a lot!

SOLUTIONS

. WHICH POTENTIAL ENERGY ON OTHER PLANETS? The same formula, but with a different constant g!

Have fun and good job!!

Your teachers’ team!