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Science |
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Middle Years Science Program
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"The
12 Tasks of Hercules"
Return to list of pracs Aim: This activity is used to make demonstrate different types of forces. Worksheets: Equipment, Method & Background Knowledge: Zeus was married to Hera. Together their son was Hercules. He was son of the God Zeus. Hera, on the other hand, was only human. Hercules needed to prove his worth by performing twelve tasks and if he was successful, he would be allowed to enter Olympus the home of the Gods and rule the world by his father's side. These tasks were difficult and varied. They required many different skills including strength, intelligence etc. Your task is to perform any six of these tasks. The choice is yours. Each time you complete one you will further strengthen Hercules for his journey towards Mount Olympus. Each task looks at a different type of force for which you are to experiment and answer questions. We begin our journey in Thessalonica in the north of Greece. Types of forces: friction, electrostatic, magnetic, nuclear, gravity, impulse(inertia), elastic, spring, tension, stress, strain, kinematics (F=ma), centripital, heat?, etc. Students are
to select in any order the 12 tasks to complete. When they have completed
a task they will get a "muscle" to stick on Hercules. He
must have all his "muscles" before continuing to Olympus.
It will also be accompanied by a map of Greece for which they colour
in the journey as they go. Hercules'
First Task: Equipment: (a) Magnets & Compasses; (b) multimeter, battery, coil of wire, wires and bar magnet; (c) battery, wires, coil and compasses. Experiments: (a) Place the compasses in a circle with the bar magnet in the middle. The needles of the compasses move around. Draw the bar magnet and draw the direction that each of the compass needles are pointing. Find out what a compass does? Take the magnets far away from the compasses. Which colour represents the north end of a magnet? (b) The multimeter measures if any electricity is made. Get the bar magnet and "throw" it through the middle of the coil of wire. Connect it to a battery. What happens on the meter? Read the information below. Why might this have happened? (c) This is a different version of part (a). Place the compasses around the coil and turn it on. What happens when you turn it on and off? Why is this happening? Information:
Magnets can be used in many different ways to make forces. Magnets
have a area around it called a field which can influence the behaviour
of metallic objects. If you get a wire and wrap it around in a coil
and then pass electricity through it you will actually create a magnet.
Electricity and magnetism are actually close relatives. A dynamo in
a bicycle has a spindle that when it is on the rear tyre and spinning,
it actually makes a magnet spin inside a coil of wire and make electricity
form. So electricity can make magnetism and magnetism can make electricity.As
for a compass, the Magnetic field of the Earth makes the compass needle
face north. The needle in the compass is a small magnet itself. Again,
there is magnetism because the Earth is spinning. Equipment: Van der Graaf generator; discharge rod; plastic bucket. Experiment: (a) Turn the Van der Graaf generator on. While one student in holding the discharge rod on the dome another student stands in the bucket and holds onto the dome. Wait for 3 minutes and watch the student's hair. What happens to the student's hair? The student in the bucket then releases the dome and touches another students hand. What happens? (b) Get the bucket with polystyrene balls in it. Turn the Van der Graaf generator off and discharge it with the rod. Place the bucket on the top of the generator and switch it on. Write down you observations. Why is this happening? Draw the Van der Graaf generator. Information: The Van der Graaf generator makes electricity. There is a belt that you can see moving around inside. It brushing against a "comb" up the top creating static electricity. The longer you hold onto the dome the more charge you obtain. The reason why your hair stands up is because electricity goes into your whole body (it makes you a battery!!!) and then into your hair. With all this excess charge in your hair, it makes each hair repel each other. Turn off the Van der Graaf generator. Alternative (if the Van der Graaf is not available) ... Equipment: Plastic ruler and small bits of paper. Experiment: Using your ruler rub vigorously on your jumper for about a minute. Then try to pick up the small pieces of paper. Information:
This is caused by static electricity. The act of rubbing the ruler
on your jumper causes the ruler to become charged. This means there
is either too many negatively charged particles on the ruler or not
enough. It can then attract other material that might also be charged
... example paper. Equipment: spring hanging from door jam with a weight attached, ruler. Weights can be a little carry basket with ball bearings etc. Experiment: Stretch the spring and release. What happens? Measure with a ruler how long the spring is. Attach one weight to it and measure the length of the spring now. Add another and remeasure. Do this for five weights. Why might it change in length? Does it change at the same rate? Think of five objects that use springs or elastic bands in it to work. Information: Springs are able to absorb great amounts of energy. A common example of this is a mouse trap. When walked on the energy is released. Cars also have springs on them to absorb the energy made when driving over bumps. These springs are found near the car tyres and measure over 30cm in length. Each spring can be measured for how strong it is. This is measured by a quantity called the spring constant. Hercules'
Forth Task: Equipment: Some sort of stand, bar magnet, string, paper clip Experiment: Raise the paper clip up so that it is suspended in the air. Why does it do this? Place objects (piece of paper, pens, book etc) between the clip and magnet and see if has any effect. If the clip does not fall then magnetism goes through these objects. Information: The clip is help up by magnetism. Magnetic forces (like all other forces are invisible) move through the air to the clip. Magnetism is able to travel through many materials, especially through air. When driving in a car, the radio often becomes hard to hear when travelling near tram tracks. The magnetic force produced by the electricity along these tracks in the main reason. In Japan, some trains rely mainly on magnets for suspension since like poles repel. Return the clip
to the table top. Equipment: Balloon, straw, masking tape, nylon wire, scissors, colour paper decorations. Experiment: Blow a long balloon up to full size. Get a straw and place two pieces of masking tape over each end and down onto the balloon. Place the nylon wire through the straw and release. What happens? Information: Can you blow on your hand hard enough to feel it being "pushed" back? As you have investigated, it is quite simple to make an object such as a balloon propel through the air a certain distance. How do larger objects such as rockets and air jets move through the air? Especially seeing that they weigh millions of times more weight. It all comes down to the sheer power and energy available by the engine. By burning high energy petrols, they are able to fly quite easily through the air and sometimes out into space.
Hercules' Sixth Task: Equipment: Cardboard, scissors, tray, water, detergent (food colouring in it) Experiment: Get a piece of cardboard about 4cm by 6cm and cut off one end as a boat. Cut a circular section out of the back with a jet stream channel as well. Place it in the tray of water and drop some of the coloured detergent into the "engine chamber". What happens? Information:
What happens when you are in a really crowded train? Its awful isn't
it? When you are crammed up against one another. What happens when
a whole lot of them leave? Do people naturally spread out? Yes. This
is what happens on the surface of water. The molecules of detergent
are much much bigger and crowded up. When it is dropped onto the surface
of water (which is sparsely scattered), the detergent molecules "push"
away from each other into relatively empty space around it. It has
the same effect as a ject engine. This is a phenomenon called surface
tension.
Hercules' Seventh Task: Equipment: Bucket, objects inside Experiment: Get the bucket with the objects inside and swing it over your head without dropping any out. Try it a few times to work out the mimimum speed you need to go so that nothing comes out. Do you go faster during any part of the swing? Information: The faster something goes around in a circle the more force outwards you would feel. This phenomenon is called centripetal force. When the bucket is at the top of the swing, gravity pulls the object down but the centripetal force forces it upwards keeping the object in the bucket. At the bottom of the swing, both centripetal force and gravity pull it down towards the earth. If you don't go fast enough at the top of the swing gravity will be stronger and therefore the objects with fall out of the bucket. Think about what happens on any spinning playground equipment. Describe what happens. If you are spinning on a swivel chair and pull your feet inwards what happens? Find out. Hercules'
Eighth Task: Equipment: Balance balls, metal balls. Experiment: Draw one ball away and release. What happens? Draw two away. What happens now? Draw three, four and five away. Investigate changing the speed of the collision and the number of balls. Drop one or two from each end simultaneously. What happens? Information:
What you are observing is a thing called momentum. If one ball is
drawn away and released the force in this one ball when it hits transfers
all the way throug the to end ball. It then moves off with the same
speed and force of the original. So the larger the force coming in
the more force is transfered through to the end. Think about what
might happen if a truck hit a mini or if a truck hits a train. What
would be the difference?
Hercules' Ninth Task: Equipment: Ten coins. Experiment: (a) Drop a stack of two and then five on the table. Do they drop at the same rate? (b) Now raise your hand to touch your right ear. Place a coin on the top of your elbow. Swing your hand down and catch the coin. "Snatch" one and then a pile of two etc. Information:
You should find that you need not swing any faster to catch one coin
as you do to catch five. Gravity works the same on every object. This
means that gravity makes everything fall at the same rate. Gravity
the force that every object (including us) experiences because of
the presence of large objects such as the earth. The reason the moon
is orbitting the earth is because of gravity. The reason all the planets
in the solar system are orbitting the sun is because of gravity. The
tides on the ocean are due to gravity. Even you are exerting gravity
on the person next to you!
Hercules's Tenth Task: Equipment: Four pulleys, some sort of stand, clamp, string, 1Kg weights, spring balance, scissors. Experiment: Set up the retort stand string and one pulley to raise the 1Kg weight up 5 cm. Measure with the spring balance how heavy it is? You can measure in Newton or in grams. Now work out a way of using two pulleys and then three etc to raise the same weight 5cm. Does it get easier? Measure all these. Information:
Pulleys are useful tools to help make life easier especially with
very heavy objects. A person can use pulleys to pick up objects that
can weight as much as a car or more!! Can you work out the relationship
between the number of pulleys and the amount of weight it measures?
Hercules' Eleventh Task: Equipment: hands Experiment: Rub your hands together really fast. What happens? Think of (and then draw) 5 situation that require friction to exist and then 5 situations where friction is not wanted. Information:
The warmth you feel comes from friction. Friction is when two surfaces
are moving againsdt each other is such a way as to stop or slow down
the motion of the other. The lost energy is converted into heat.
Hercules' Twelth Task: Equipment: 1Kg weight, string or nylon wire suspended from ceiling. Experiment: Suspend a 1Kg weight from the ceiling with the nylon wire. Stand to the side of it and hold the 1Kg weight up to your nose. Let it swing away from your face and back to you again. Stand a little bit back from it the first few times and then you can be a bit more daring. Will it hit your face? Are you willing to give it a go? Information: The equipment you have set up is a basic pendulum. In theory it should not hit your nose. The amount of height it has gained if it was hanging straight down gives it gravitational energy. When you pull it up to your nose you give it that energy. When you release it is converted to movement energy (called kinetic energy) as it swings through the bottom and then on the other side converts back to gravitational energy and therefore stops again on the other side.
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