Simple Machines

Simple Machines
Machines make work (the application of a force to move an object) easier. Machines enable us to increase a force and speed of an object; machines enable us to change the direction and location of an object. A machine does work by increasing a force (push/pull) on an object. Machines are concerned with two forces-the effort force (push or pull we apply) and the resistance force (weight of the object being moved). Furniture movers do work when they move boxes; gardeners do work when they hoe weeds. Machines make this work easier. Furniture movers use a ramp to slide the boxes onto a truck;a gardener uses a shovel to dig out the weeds. The ramp and the shovel are simple machines and make moving boxes and pulling weeds easier. There are six types of simple machines that make work easier.

Levers help us move and lift objects. All levers (or bars), regardless of shape, have three parts.
1. Fulcrum-the point at which a lever swings, turns, or balances on.
2. Effort-force (push/pull) we apply
3. resistance- the object/load we want to move or lift.
Levers are divided into three categories
1. First Class- the fulcrum is located between the effort force and the load. Example: crow bar, see saw, hammer. With a hammer, the effort is the push or pull on the handle, the load is the claw that grasps the nail to be taken out of the wood, and the fulcrum is the head of the hammer which swings and turns as you push the hammer to take out the nail. First class levers work best when the fulcrum is near the resistance/load. Try the discovery activity in you science book on pg. 274 "Move Those Loads: Making and Using a Lever"... It works! This is an animation of a see saw lever from discover.edventures.com

2. second class- The load is located between teh fulcrum and effort. Example: wheelbarrow. The effort is the push we apply on the handles, the load is the bucket full of stuff, and the fulcrum is the will which allows lift and movement for transport.
3. third class- The effort is between the load and fulcrum. Example: broom. The fulcrum is the handle which swings as we apply force. the load is the dirt we sweep.

A pulley helps us lift and move stuff. A pulley is a rope around a wheel with a groove along its edge to hold the rope. You would pull the rope down on one side of the pulley to move or lift a weight on the other side of the rope. There are two types of pulleys...
1. fixed or in place pulley- good to move stuff but doesn't make it easier to lift heavy stuff. It acts as a first class lever with the fulcrum located at the axel. It doesn't make lifiting easy because the fulcrum and distance from the load is equal. Remember: levers work best when fulcrum is closer (not equal) to the position of the load. Example of a fixed pulley is a flag pole.
2. movable pulleys reduce the amound of force needed to lift a load. It works as a second class lever, moves the load, and has mor ropes. picture of a fixed pulley from kosmoi.com


Wedges are double inclined planes. Wedges push under or into the load. Wedges work best when it is long and thin. Examples of wedges include axe, nail, needle. image found at staff.harrisonburg.k12.va.us

An inclined plane is a slanted surface/higher on one side and lower on the other side. An inclined plane makes moving heavy objects easier. This surface allows one to apply only a small amount of force to move a heavy object over a longer distance. Inclined planes work best when they are longer. Examples include a ramp and staircase. image found at kosmoi.com

A screw is an inclined plane wrapped around a cylinder. Screws hold things together. Examples of screws include the jar and lid, screw. image from www.harmsco.com


A wheel and axle helps move things, lift things, and speed things up. A wheel is attached to a handle that turns in the same direction. Examples include bicycle pedals, door knob, and screwdriver. With a screw driver, the handle is the wheel portion which moves with a push, and the shaft/bar is the axle.

More examples of simple machines we use everyday
Activities with simple machines

Toxoplasmosis

Image from thecatgallery.com

What on earth is Toxoplasmosis?
Toxoplasmosis is caused by a parasite found in infected cat feces, undercooked meat, and unwashed vegetables. One may transmit Toxoplasmosis by accidentally ingesting infected cat feces by putting one's hand to the mouth after cleaning the litter box or digging in the garden, or touching anything in contact with infected cat feces. Of those who are infected, very few have symptoms because a healthy person's immune system usually keeps the parasite from causing illness. However, pregnant women and individuals who have compromised immune systems should be cautious; for them, a Toxoplasma infection could cause serious health problems.

Cats only spread Toxoplasma in their feces for a few weeks following infection with the parasite. Like humans, cats rarely have symptoms when first infected, so most people do not know if their cat has been infected. The infection will go away on its own. Cats generally get infected by eating an infected rodent.

Some people who have toxoplasmosis may feel as if they have the "flu" with swollen lymph glands or muscle aches and pains that last for a month or more.
Severe toxoplasmosis, causing damage to the brain, eyes, or other organs, can develop from an acute Toxoplasma infection or one that had occurred earlier in life (in babies who were infected in the womb) and is now reactivated. Severe cases are more likely in individuals who have weak immune systems, though occasionally, even persons with healthy immune systems may experience eye damage from toxoplasmosis. Symptoms of ocular toxoplasmosis can include reduced vision, blurred vision, pain (often with bright light), redness of the eye, and sometimes tearing.

Who is at risk of severe toxoplasosis?
Infants born to mothers who have not became infected with Toxoplasmosis for the first time during or just before pregnancy are at risk. In other words, if a woman receives her first exposure to Toxoplasma while pregnant, the baby is at particular risk via the placenta. Persons with severly weakened immune systems are at risk.

Rocks

What is a rock? To know what a rock is, we must know what a mineral is. A mineral is an element or combination of elements that form a compound. Many mineral compounds include a combination of elements (usually oxygen and other elements). Silicon, quartz, graphite, gem stones, and gypsum are minerals. A rock is an assemblage of minerals bound together. Granite is a rock composed of several minerals including quartz. Three types of rocks are formed by processes that interact in the rock cycle. You may view this slide show to see and learn more about different types of rocks and minerals
The three types of rock and how they are formed...
The igneous rock is formed from the heating and cooling of magma (melted/molten rock). When the magma erupts from a volcano, the magma is called lava. How fast the lava cools determines its texture. Hawaii is formed from igneous rock, mainly basalt. Igneous rocks include pumice, granite, and basalt.
Sedimentary rocks are formed from existing rocks. Water, wind, erosion breaks down the rock into pieces. Water, wind, ice, and gravity transport the pieces to other sites where the pieces are deposited. The pieces settle and form horizontal layers. Over a long time, the layers (strata) become pressed together in a process called lithification. Sedimentary rocks are weak and crumble easily. Sedimentary rocks include sandstone, limestone, and shale.

Sedimentary rock is distinctive because it is made up of layers, each of which has a different color.

Do you notice the different layers and different colors in this rock?
http://comp.uark.edu/~sboss/seds02.jpg


This is pahoehoe lava which will form basalt rock in Hawaii.

Metamorphic rock is formed by any rock, either igneous or sedimentary, which is transformed into a whole new rock by extreme heat or extreme pressure. Metamorphic rocks are hard and tough (compared to sedimentary). Metamorphic rocks include marble and shale.
The Rock Cycle
All three types of rock interact and are continuously being recycled into various rock forms. For example, igneous rock may be broken down into little pieces and later form sedimentary rock.

http://volcano.und.nodak.edu/vwdocs/vwlessons/lessons/Metrocks/Metrocks2.html



I found an excellent lesson where students learn about the rock cycle and properties of rocks by experimenting with crayons, observing crayons, and relating those observations and processes with the three types of rocks and how they all interact in the rock cycle.

Go Bananas!!!!!

What's so good about bananas, how do they ripen, and why should you "go bananas"...

Bananas are one of my favorite fruits because bananas are sweet and yum yummy. If you have a fruit-full banana tree in your backyard, I'm sure you've had too many bananas that became ripe and then became rotten at the same time. There are ways to speed and delay the ripening process. Also, bananas are so nutritious, they should be part of your daily fruit servings.

make a banana smoothie...http://www.smoothie-recipe.com

Gas... and ripening

Most fruits give off an ethylene gas in the process of ripening. Because bananas release a higher concentration of ethylene gas, they ripen quickly. If you've bought green bananas and want to accelerate the ripening, place them into a paper or plastic bag and at room temperature. Humidity and warm temperature helps induce ripening. The paper bag holds the ethylene in stagnant air around the fruits, yet allows oxygen to go into the bag for respiration in the fruits... If you have other fruits that you would like to ripen, place them in the bag (where there is increased exposure to ethylene gas) too.
If you have too many green bananas, you can allow the bananas to ripen to the stage you like them and then put them in the refrigerator. This slows the ripening process down. WARNING: the peels will turn brown and my interfere with further ripening.

Bananas and Healing

Bananas contain potassium and magnesium which alleviate blood pressure, cholesterol, and risk for stroke. Bananas keep blood sugar levels up and helps alleviate morning sickness. Bananas contain fiber which helps alleviate constipation. Bananas alleviate heartburn, mosquito bites (by rubbing inside peel on bite), and hangovers. Trying to quit smoking? potassium and magnesium found in bananas help the body recover from the effects of nicotine withdrawal.

Remember...eating 5 to 9 servings of fruits and vegetables a day provides a variety of health benefits. Fruits and vegetable are rich in vitamin C, vitamin A, fiber and other nutrients. Along with physical activity and maintaining a healthy weight, eating 5 to 9 servings of fruits and vegetables a day promotes good health and reduces the risk of cancer, heart disease, hypertension, stroke, diabetes, and other chronic diseases. One banana may be counted as one serving. Refer to the food pyramid for more information on eating healthy.

Jewels of the Forest

What's the big deal about the native Hawaiian tree snails?

Image from Hawaii Forest and Trail

• These snails are not very ambulatory. Some are thought to stay in the same tree (usually Ohia or Kopiko trees) their whole life. Because of this, it was easy for populations to become isolated and change. Because the snails are isolated on island ridges and in lush valleys, they changed and developed into a different species. Each species has its own spiral coloration diverse in patterns, colors, and shapes. The shells are glossy and oblong. Because of the shells' beautiful coloration, the snails are known as jewels of the forests.
• Tree snails give birth to only one or two babies a year.


• Today, many of the species are extinct, and the remaining populations of Hawaiian tree snails have been classified as endangered. On the island of Oahu, all species of the genus Achatinella, also known as the O`ahu tree snails, are federally listed as endangered.


• The snails don't eat their native host plant. The snails are fungus eaters and are especially fond of black sooty mold. By gleaning the leaves of mold they assist in photosynthesis and keep the plants healthy.

Threats to the species...

• The achatinella and other various species were so beautiful and plentiful that local residents collected them by the thousands in the 1800's.


• Predation has also played a significant role. Once rats made it to the islands, they found the snails to be quite delicious. Even more insidious than rats was the deliberate introduction of the carnivorous snail Euglandia to the islands. Originally brought to the islands and released in 1955 to control the alien African snail, which is an agricultural pest and an intermediate host for cattle liver fluke, it soon found the Hawaiian snails easy prey. In a few years the euglandia made its way from the lowlands up into the native forests and remaining pockets of native snails disappeared. Increased urban construction has crowded out native snails.

Image from www.hawaii.gov/dlnr/Aliens2.html

Image of euglenia snail from www.naturesrepellent.com/images/rosy.jpg

Resource Links

Hawaii forest and trail

U.S. Fish and Wildlife Service

Solar Energy

When I was a sixth grader at E.B. deSilva Elementary, I had a fun teacher who embraced science. My teacher enabled me to explore the earth's processes and elements with fun activities and experiments. One of the lessons focused on solar energy. One of the science activities I performed was the building of solar ovens. I remember building the solar oven that used the sun's energy to cook pizza bagels, but I don't remember much about what solar energy is, how solar energy is used, and how a homemade solar oven works. This leads me to further wonder and investigate...

What is solar energy?
Solar energy just means energy (light or heat) that comes from the sun. For example, plants use solar energy (light) to grow. Solar energy heats the inside of our cars during a hot and sunny day.

How can we use solar energy?
There are two basic ways that we can use solar energy. We can use the sun's energy to heat things--our houses, the water in our houses, the food in a solar cooker, and so on. This is called solar thermal energy. (Thermal means heat, so solar thermal energy just means heat energy from the sun.) The second basic way we can use solar energy is to turn light from the sun directly into electricity, using solar panels.


Solar electric panels are made up of something called silicon, the same thing that makes up sand. There is more silicon on the planet than almost anything else. Even though you can find silicon almost everywhere, making a solar panel is difficult and expensive. The silicon has to be heated to super high temperatures in a big factory, and then formed into very thin wafers. When sunlight hits a solar panel, it makes electrons in the silicon move around. (Electrons are teeny tiny specks--they're way too small for us to see, even under a microscope.) The electrons flow through wires that were built into the solar panel. And presto! We have electricity! We can do whatever we want with this electricity, run a calculator, a CD player, or, if we have big enough solar panels, a satellite! [Solar panels are also called photovoltaic panels. "Photo" means light and "voltaic" means electricity.]
When the sun stops shining on your solar panel, its electrons stop moving and electricity stops flowing. So what do you do if you want to be able to read or watch television at night? (But you don't watch television, do you?!) What stores the electricity in a flashlight? Right! A battery! And that's exactly what people do with solar panels... they attach batteries. The batteries are big, heavy, rectangular boxes, sort of like car batteries. Electricity from a solar panel flows into attached batteries while the sun shines, and then the stored electricity in the batteries can be used at night, or when the sun is behind the clouds.

You have probably seen big panels on the roofs of houses. These panels are used to power the house with electricity provided by the sun!!!

To read more about solar panels and solar energy, look at this excellent site on solar energy


How does a solar oven work?
We can use solar energy, or the heat from the sun, to cook our food in a solar oven. A solar oven is an insulated box with a transparent top and a reflective lid. The box usually has one or more reflectors with aluminum foil or other reflective material to bounce extra light into the interior of the box. The inside bottom of the cooker should be dark-colored or black. The inside walls should be reflective to reduce radiative heat loss and bounce the light towards the dark bottom. We can make our own solar ovens from our own pizza boxes or shoe boxes. Solar ovens are great because they save energy and minimize pollution. It is a lot of fun to cook and then eat your own pizza in your own homemade solar oven.


Make Your Own Solar Oven
What you need:
shoe box or pizza box (ask a pizza restaurant to give you one, a square box is best)
ruler
marker or pen
scissors
plastic wrap
aluminum foil
tape or glue (it should say 'non-toxic')
drinking straw or stick
black paper (newspaper may also be used as an alternative)
a sunny day
pizza bagels, hot dogs, or marshmallows with graham crackers (for s'mores)

1. Draw a square on top of the pizza box. Make it one inch away from the edges. Have an adult cut along three sides. Do not cut the line along the back of the box.


2. Make a flap by folding back along the uncut line.3. Cut a piece of foil to fit the inside of the flap. Glue or tape the foil in place, shiny side out. If you put it on carefully, it will not wrinkle much. Press out any wrinkles with your fingers. 4.Cut the plastic to fit over the hole that the flap made. Make sure the plastic is much bigger than the hole. Tape the plastic to the box. Seal the plastic tightly so that the air cannot get out.5. Cut another piece of foil to cover the bottom and sides of the box. Glue or tape the foil into place. 6.Cover the foil with black construction paper, and tape it into place. 7. This is what your finished solar oven will look like...8.To cook something... lay a piece of foil in the center of the box. You can also use a napkin or paper plate. Put the hot dogs, pizza bagels, marshmallows/crackers, etc... on the foil. 9. Close the box. Open the flap of the box. Prop the flap open with the drinking straw or stick. Turn the flap towards the sun. You want the sun to reflect off of the foil and into the box. It may take about an hour to cook a hot dog; solar ovens are slow cookers.
Take a look here for more information on how to make solar ovens, and here for more information on solar cooking.

The Sky

When the sun shines brightly and a few clouds scatter the sky, the sky is blue. We see the sky everyday, and yet the sky is always blue. Except during cloud coverage and sunsets, the sky never eludes its blue color. Because I see the blue sky everyday, I have always wondered why the sky is blue and not green or purple.

Here is a science made simple link about why the sky is blue

The sky is blue because of the light that enters our eyes.
Before we answer the question, "Why is the sky blue?" we must first know what light is.
The reason we all are able to see with our eyes is that light enters our eyes. Light exhibits the characteristics of a wave. Light's waves may be visualized as a curvey line.

Waves display a pattern of alternating crests (the top curve of a wave) and troughs (the bottom curve of a wave). The distance from one crest to another is the wavelength.





A wave, wavelength (distance between crests), frequency





A wave, crest (the top), and trough (the bottom)

All waves have a frequency. The frequency of a wave is the number of waves that are made per second.



Take a look at this link to see an animation of wave frequency



As the frequency of a wave increases, the wave length decreases. As the frequency of a wave decreases, the wave length increases. The frequency of a wave of light determines the light's color. When sunlight is separated, the light is separated into many different colors. Sunlight may be separated through a crystal prism, glass, or rain drops. Rainbows are created by the seperation of the sun's light through rain drops.

sunlight may be separated into colors by raindrops...rainbows!

The earth's atmosphere also has a role in separating the sun's light. The atmosphere is composed of oxygen and nitrogen gasses. Blue light has a high frequency and a short wave length. The wave length of blue light is about the size of an oxygen atom. Because of the wave length the size of an oxygen atom, blue light interacts with the oxygen in the atmosphere. The light is scattered by this reaction. Because the scattered blue light enters our eyes from many different angles, we all see the entire sky in the color blue.