JET PROPULSION - Johnno's Science



JET PROPULSION

What You Need

|2 balloons | |4 metres of string |

|1 clothes peg | |1 scissors |

|1 straw | |2 pieces of tape |

What You Do

1. Cut about 1/4 of the straw off.

2. Stick the short piece of straw part way into the neck of one of the balloons. Tape the neck tightly around the straw.

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3. Thread the longer piece of straw onto the string. If it will not go through, you can suck it out.

4. Tie the ends of the string between two chairs or desks so that the string is tight. Put the straw at one end of the string.

5. Blow up the plain balloon so that it is about the size of your face. Twist the end and clip it shut with the clothes peg.

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6. Tape the balloon under the straw on the string. Which way do you think the neck should point if we want the balloon to travel along the string?

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7. Take the clothes peg off and let the air out of the balloon. What happens? How far does the balloon go?

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8. Predict: What do you think would happen if the balloon had more air in it?

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9. Try it and record what happens.

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10. Predict: What do you think would happen if the balloon had less air in it?

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11. Try it and record what happens.

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12. Now blow up both balloons so they are the same size, about the size of your face. When both are ready, let the air out so that it blows on you. Which balloon has more air coming out?

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13. Predict: What do you think will happen if you repeat steps 5-7 using the balloon with the straw? Look back at your notes to remind yourself what happened with the plain balloon.

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14. Try it and record what happens.

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Think About It

How can you explain what happened when you used different amounts of air?

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How can you explain what happened when you the two different balloons?

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ARTIFICIAL GRAVITY

What You Need

|2 paper plates | |1 ruler |

|1 large bead | |1 stick |

|1 scissors | |8 pieces of tape |

What You Do

1. First, build your space station. Mark the centre of both paper plates. Poke a hole with the stick through the centre of each plate.

2. Mark a circle on one paper plate about one inch from the edge. Also draw two lines through the middle of that plate about one inch apart as shown in Figure 1.

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3. Cut out the shaded areas shown above in Figure 2 on just one plate.

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4. Put one paper plate upside down on top of the other plate. Tape the edges together in eight places as shown in Figure 3.

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5. Put the stick through the two holes in the centre and practice spinning your space station while your partner holds the stick.

6. Hold your space station so the cut open part of it is facing up. Put the bead in near the middle. We will pretend the bead is an astronaut.

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7. Spin your space station and write down what happens to the astronaut. (If the astronaut falls out, put her or him back in and try again. Try spinning a little slower.)

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8. What do you think will happen to the astronaut if you tip the space station like in Figure 5 while it is spinning?

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9. Try spinning the space station again. While one partner keeps the space station spinning, the other partner should tip the stick. What happens to the astronaut?

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Think About It

When the space station was spinning, we created artificial gravity that kept the astronaut from falling out. Which direction is "down" for your astronaut?

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MOON SHADOWS

What You Need

|1 flashlight | |1 small ball |

|1 large ball | |1 thick book |

|2 toothpicks | |1 push pin |

|clay | | |

What You Do

1. The large ball will be the Earth, the small ball will be the Moon, and the flashlight will be the Sun. Remember, never look directly into the Sun! Stick a toothpick into the Earth and another into the Moon.

2. Put the other end of the toothpicks into two balls of clay. Flatten them so that the clay makes the Earth and the Moon stand up on their toothpicks.

3. The push pin will be you. Stick yourself on the Earth somewhere near the equator.

4. Set the Sun up on top of a thick book or a few thin ones. The centre of the Sun must be the same height as the centre of the Earth and Moon.

5. Set up the Sun, Earth, and Moon in the order shown in the figure. Turn the Earth so you are on the side away from the Sun. Turn on the Sun. Is it day or night where the model of you is? _______________

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6. Now let the Earth rotate so that "you" are on the side by the Sun. Is it day or night for you? ___________________

7. Let the Earth rotate some more until you are half way between the Sun and the Moon. What time of day is it for you? ________________

8. Now let's see how the Moon can change things. Turn the Earth so that it is daytime for you.

9. Start the Moon revolving around the earth slowly. Watch what happens to your daylight as the Moon comes between the Earth and the Sun. What did you see?

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Think About It

In step 9, you created a solar eclipse. This can make it get dark in the middle of the day. What causes this darkness?

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PHASES OF THE MOON

What You Need

The Moon

Record Sheets

What You Do

1. For the next several weeks your class will be astronomers that are observing the moon. Each night, one or more students will go outside, find the moon, and draw a sketch of it. If it’s rainy or cloudy, write that across the moon on the observation sheet.

2. Write down what time you made your observation. Also record the date, your name, and your team.

3. Your class can tape these sheets together, in order, to see the moon go through its phases.

Think About It

Once your class has finished making observations, figure out how long it takes for the moon to go through a full cycle. Explain how you got this answer.

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CREATING CRATERS

What You Need

|1 flat pan | |2 slips of paper |

|1 craft stick | |2 pieces of tape |

|1 golf ball | |sand - get this when needed |

|2 toothpicks | | |

What You Do

1. Make your flags. Write each of these words on one slip of paper: knees and face. Tape each slip to a toothpick to make a flag.

2. Fill your pan with sand and smooth it out flat with the craft stick. This will be the surface of a planet. Put the pan on the floor.

3. Stand next to the pan. Hold the golf ball face high and drop it into the pan. This will be like a meteor crashing into the planet. Carefully remove the "meteor" and mark the crater with its flag.

4. Hold the meteor knee high and drop it into the pan. Carefully remove it and mark the crater with its flag.

5. Observe the craters you made. Describe any differences among them.

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Think About It

How are your craters the same as those found on the moon and planets?

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How are they different?

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GALILEO'S GRAVITY

Background

A long time ago, there were two scientists: one named Aristotle and one named Galileo. Aristotle thought that the Earth's gravity would pull heavier objects down faster than lighter ones but he never did the experiment. Galileo wanted to find out for sure so he designed an experiment where he dropped a heavy ball and a light ball off a tall tower at the same time. Which one do you think hit the ground first?

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What You Need

|1 golf ball | |1 pair of safety goggles |

|1 tissue | |1 Ping-Pong ball |

|1 flat pan | |sand - get this when needed |

What You Do

1. Fill the pan part way with sand to make a soft place for the balls to fall. Which ball is heavier, the Ping-Pong ball or the golf ball?

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2. Put the pan on the floor. One partner should put on the safety goggles and get down on the floor so she or he can see which ball hits the ground first.

3. The other partner should hold both balls at shoulder height above the pan. Count to three out loud (so your partner will be ready) and then drop both balls at once. Which one hits first or do they both hit at about the same time?

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4. A tissue weighs about the same as a Ping-Pong ball. Which one do you think will land first?

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5. Try it and record what happens.

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Think About It

What did you learn about gravity from Galileo's experiment?

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THE SOLAR SYSTEM

What You Need

|5 sheets of yellow paper | |copies of the planets |

|15 sheets of white paper | |cellophane tape |

|scissors | |markers or crayons |

|glue stick | | |

What You Do

1. Tape each of the yellow papers together along their short edges. This will represent the Sun.

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2. Tape the 15 sheets of white paper together along their short edges. This is where you will put the solar system. Number each page in the top right corner.

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3. Tape the edge of the Sun to the edge of the solar system.

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4. Colour in each planet. Add moons or more rings if you want. Do not cut them out yet.

5. One at a time, cut out the planets and put them in the solar system. Next to each planet is a map that shows you where to put the planet. First, it tells you the number of the page where the planet goes. Then, it shows you where on the page the planet goes.

6. Label each planet.

7. Add other members of our solar system such as comets and meteors.

Think About It

What did you learn about the sizes of the planets or their distances from the sun?

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THE EXPANDING UNIVERSE

Background

Scientists believe that the Universe is expanding. Let's see what this means for the distances between Earth and the stars.

What You Need

1 light coloured balloon

1 ruler

1 clothes pin

3 markers in different, dark colours

What You Do

1. We'll use a balloon to represent the Universe. Blow up the balloon to the size of an egg. Twist the end and hold it closed with the clothes pin.

2. Make a dot for the Earth. What colour did you use? ______________

3. Using a different colour, make a dot 2 cm away from the Earth. This will be a nearby star. What colour did you use? ________________

4. Using the last colour, make dots all over the balloon to represent stars all over the Universe. What colour did you use? ______________

5. Let the Universe expand by blowing up the balloon until it is the size of your head. Twist the end and hold it closed with the clothes pin.

6. What is the distance between Earth and the nearby star that you marked in a special colour? ________________ centimetres Is this closer or further away than at the start? _________________

Think About It

What happened to all of the stars?

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If you could make time run backward, the Universe would contract rather than expand. Where would all of the stars end up?

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TEACHER'S NOTES

These activities are generally designed for the kids to work in pairs unless otherwise specified. If you have an odd number of students in your class, make one team of three. A list of the materials that are in the kit and those which you must provide is at the end of these notes.

Phases of the Moon will take from 4-6 weeks so it should be started early. In general, the experiments (not counting class discussions) should take about 1/2 hour except where noted. I recommend doing the experiments in the order in which they appear in the book.

MOON SHADOWS

Purpose:

The purpose of this activity is to model how day and night occur and to observe that a solar eclipse is nothing more that the shadow of the moon falling on the earth.

Preparation:

Review the concepts of rotation and revolution and how the Earth, Moon and Sun move in the solar system. Review what the equator is. Talk about eclipses and the importance of not looking at the sun directly.

The kids will need to use a thick book or several smaller ones to hold up the flashlight.

PHASES OF THE MOON

Purpose:

The purpose of this activity is to observe the phases of the moon and that they are cyclical. The observations must be done at home (at night), however, the data analysis can be done in class.

Preparation:

The Moon is only bright because it reflects light from the Sun. And the Sun can only light up the half of the Moon that is facing the Sun. So, depending on where we are when we look at the Moon, we may see a complete circle of light, or no light, or a crescent.

Talk about what the new moon and full moon are. Also talk about astronomers and how they derive their knowledge from making many, many observations of the night sky.

Form your class into teams of seven students. Assign one student on each team a certain day of the week. It will be her/his job to make the observation that night every week for at least 4 weeks. Since the moon's cycle is 4 weeks long, making observations for 5 or 6 weeks will show your class that the cycle is repeating.

If your class is not an even multiple of seven, split the extra kids among the teams. You can have two of your less reliable kids make observations the same night or have each child make observations every 8-9 days (depending on the number of team members) rather than once a week. If someone forgets to make an observation, just have them write "no observation" across the moon on their record sheet.

You will need to make at least four copies of the record sheet for each child. As the kids bring in their observations, tape them together, in order, for each team. Hang them in the classroom so the kids can watch the phases changing.

CREATING CRATERS

Purpose:

The purpose of this activity is for the students to observe how craters are made and to encourage them to carefully observe photographs of the moon and planets.

Preparation:

Review with your class what craters are and how they're made. Have on hand some pictures of craters so that they can compare theirs with real ones.

Note that the higher you hold the ball, the faster it is going when it hits the pan. Therefore is should make a larger crater.

Cut up 24 slips of paper approximately 2 x 4cm. Have a few buckets of sand available with a cup or scoop in each. When they are done, the kids can dump the sand from their pans back into the bucket. Put newspaper under the buckets to help make clean-up easier.

GALILEO'S GRAVITY

Purpose:

The purpose of this activity is to explore gravity and learn, as Galileo did, that it pulls all objects to Earth at the same rate (except, of course, if there is wind resistance).

Preparation:

This is an excellent opportunity to introduce some early scientists and how scientific ideas and methods change over time.

The ping pong ball and golf ball are approximately the same size and shape but are different weights. Unlike what Aristotle thought, they will (should) both hit the ground at the same time. The tissue is approximately the same weight as the ping pong ball however, it is wide and flat and so will have air resistance counteracting gravity. If you were to crumple it into a ball, there would be less air resistance and it would behave more like the other balls.

Have a few buckets of sand available with a cup or scoop in each. When they are done, the kids can dump the sand from their pans back into the bucket. Put newspaper under the buckets to help make clean-up easier. Dropping the balls into a pan full of sand is simply to keep them from bouncing all over the classroom.

You will need to have safety goggles available for the child who is observing near the floor. This is to prevent sand from getting in his/her eyes. A broom and dustpan will be needed to clean up spilt sand.

FLY AWAY MOON

Purpose:

The purpose of this activity is to help the kids see that gravity keeps the Earth and Moon together and that, without gravity, the Moon would fly away from the Earth in a straight line.

Preparation:

Talk about gravity and what it does for us. Talk about times when gravity gets in the way. Review that every object has gravity and that "down" is in the direction that gravity pulls things. The furthest down you can go on Earth is the centre of the Earth.

The kids will need to know their weight so ask them to find out for homework. If they can't find out, have them use 20 kg for a small child or 28 kg for a large one. These numbers are both divisible by 4 to make the math easy.

Your class will also need to be familiar with basic fractions (1/2 and 1/4) and how to figure out what 1/4 of something is or what 2 1/2 time something is. They can use manipulatives, calculators, or draw a picture to help their computations.

The actual gravitational pull on the Moon is from 1/6th to 1/4th of Earth's. The actual gravitational pull on Jupiter is 2.63 times that of Earth's. These numbers were rounded to 1/4 and 2 1/2 to make the calculations easier for the students.

There will be paper towel balls flying around the room but, since they are soft, no one is likely to get hurt. Make sure the kids have plenty of space around them before they start spinning their "moons". This would be a good activity to do outside if the weather permits. Use thin string about 60cm long.

ARTIFICIAL GRAVITY

Purpose:

The purpose of this activity is to introduce the idea of artificial gravity that might be used in spaceships and space stations. In the case of a spinning space station, "down" actually is in the direction of the outside edge.

Preparation:

Review the idea of weightlessness in space. Talk about what it would be like and how difficult certain things (like eating and going to the bathroom) would be.

If the kids have trouble spinning the space station from the outside, have them put one finger inside and spin their hand in small circles. The astronauts occasionally come flying out of the space stations. Since they are wood, no one should get hurt. If there are no beads available, you can make balls (about 1 – 2 cm in diameter) out of aluminium foil.

For sticks, use 25cm bamboo skewers. The pointed end can be used to poke the holes. If necessary, a push pin can be used to get the holes started. Save the skewers; they can be reused. You'll have to provide scissors and rulers.

JET PROPULSION

Purpose:

The purpose of this activity is to introduce the idea that air being forced out of an object causes that object to move in an opposite direction. The activity also provides an excellent opportunity for the kids to practice predicting and then testing their predictions.

Preparation:

Explain to your class that the "space" in front of them is not empty but full of air molecules and that these molecules are always moving. Outer space, on the other hand, is "empty". Talk about rockets, spaceships, and other vehicles and how they move. Consider discussing the idea that, "For every action there is an equal and opposite reaction." As the air molecules leave the balloon spaceship, their action causes the spaceship to "react" by moving in the opposite direction. The spaceship will go faster if the rate of the air leaving the spaceship increases.

Use large balloons, at least 30cm in diameter, since they are easier to blow up. If they are still difficult to blow up, stretch them first. Each child should blow up one balloon. Remind them not to switch balloons to avoid exchanging germs.

Use masking tape for this exercise since it will form a better seal between the balloon's neck and the straw than cellophane tape.

THE SOLAR SYSTEM

Purpose:

Help your kids become intimately familiar with the solar system by having each child construct a 4m long, almost to scale model! They can do this in pairs or by themselves so they can take the model home when they are done. This activity takes about 2 hours and lots of floor or table space.

This solar system model is not entirely to scale; rather, it is to two different scales. The sizes of the planets are all to a scale of 26 km per 2cm. The distances between the planets and the sun are also to scale relative to each other. This scale is approximately 37,000,000 km per 2cm. If the distance from the sun were on the same scale as the size of the planets, the earth would be approximately 150m from the sun!

Preparation:

You will need to photocopy one set of planets for each student or team:

Mercury, Venus, Earth, and Mars

Jupiter

Saturn

Uranus, Neptune, and Pluto

The solar system is assembled on 15 sheets of white paper taped together along their short edge. Fanfold computer paper works well for this and eliminates the need to tape the sheets together. Tear apart packets of 15 sheets each.

The sun is represented by 5 sheets of yellow paper taped together along their short edge. This is the diameter of the sun on the scale used for planet diameters. The sun could be made as a circle of this diameter (2m), but it is more manageable to just use the strip of paper.

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THE EXPANDING UNIVERSE

Purpose:

To help your class visualize the concept of the expanding universe and the idea that stars are constantly moving further away.

Preparation:

Review what the universe is. Make sure your class can measure with a ruler.

One theory of the creation of the universe is the Big Bang theory. That has all of the matter of the universe in one place until a giant explosion sends it flying out in all directions. Stars and planets form but they keep moving out. The further out they go, the more their light appears shifted to the red end of the light spectrum, the "red shift". Observation of this red shift helped develop and support the Big Bang theory.

Use balloons that are at least 30cm in diameter so they are easy to blow up

MATERIALS

|For a class of 24 (reusable): |

| |2-4 buckets for the sand |

| |4-8 cups to scoop up sand |

| |4 sticks of clay, cut into 12 pieces |

| |16 litres or 20kg bag of sand |

| |12 flashlights |

| |12 2.5 cm styrofoam balls |

| |12 2.5cm styrofoam balls |

| |12 craft sticks |

| |12 pie pans |

| |12 clothes pegs |

| |12 push pins |

| |12 bamboo skewers |

| |12 1.5 cm wooden beads |

| |12 golf balls |

| |12 1pieces of thin string |

| |12 Ping Pong balls |

| |12 scissors |

| |12 rulers |

| |12 pairs of safety goggles |

| |24 toothpicks |

| |thick books |

|Replace for each class of 24: |

| |12 straws |

| |24 30cm balloons |

| |24 paper plates |

| |24 toothpicks |

| |40m of thin string |

| |cellophane tape |

| |masking tape |

| |newspapers |

| |scrap paper |

| |yellow and white paper |

| |paper towels |

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