Gravity Prezi

FRICTION!

Our class tested friction on cars using a ramp and we also tested the cars in different places. We tested the cars on carpet(in our classroom), on the concrete and on a downwards facing surface wich was also concrete. Some of the variables were: Bark, stones and mud. surfaces. people. wheels and the design of the car. Friction was used in this experiment becuase every car that went down the ramp used friction and all the cars had a different design. So that means every car had a different ending. Some cars went faster than others, and some cars went slower than others. Friction acted on the cars very differently. Thats why some cars went faster than the others. The surface also impacted on the cars differently.

Some cars were designed to go on soft surfaces while others were ment to go on hard and rough surfaces. When our class did this, we all predicted how many centimetres or metres the car would go. Friction is when two things rub together. If you rub your hands when their dry, it makes friction. It also makes your hands warm. If you rub your hands with soap on them, it does make a little bit of friction but not much. It dosn’t make your hands that warm either. If you rub two rocks or sticks together for sometime, it makes friction and it is very hot. If you rub two sticks or rocks together for a very loooong time it can make fire. Friction slowed the cars down because when the cars rubbed against the ramp it made friction and friction slows things down. If friction wasn’t there then if you rolled something it would roll on for ever and ever…

BOTTLE ROCKET PROCEDURAL TEXT!

Goal: To make our bottle rocket fly. Materials:

• 1 bottle
• 3 teaspoons bi-carb soda
• A quarter cup vinegar
• Things to decorate the bottle with(optional)
• Cling wrap

1.Decorate the bottle(optional).

2.Add the vinegar in the bottle.

3.Lay the cling wrap down and put the Bi-carb soda on and wrap it with cling wrap.

4.Put the Bi-carb soda with the cling wrap into the bottle.

5.Put the lid on and shake thoroughly.

6.Stand in a safe place and hold the bottle down.

7.Let go of the lid and watch the your bottle fly!

If you don’t listen to these steps you will be doomed…                                 By Asmetha!

 

Gravity!

Objects that have mass pull on each other. We call this the pull of gravity. Gravity always pulls objects together. It never pushes them apart. The strength of the pull between two objects depends on two things. The first is the massof both of the objects. The larger the masses the stronger the pull of gravity. The second is the distance between the objects. The smaller the distance the greater the pull of gravity. Both of the objects will feel this pull equally. A pull (or a push) is a force. So this is the force of gravity.

 

 

The Earth tries to pull everything down towards its centre. This pull is called the force of gravity. When you lift things up you have to pull against gravity. If you drop a pencil, gravity pulls it to Earth. If you rest its mid-point on your finger, gravity will pull down equally on both sides of the pencil and it will balance in the air.Did you know that there is no gravity in space? This is why astronauts float around in their spaceships.

 

Did you know that there is gravity on the Moon? The gravity on the Moon is much weaker than the gravity that we have here on Earth. This is why moon walking for astronauts is very difficult.

Here is an experiment that has got to do with gravity:

Materials you will need:

• Water

• Bucket with a handle

• An Arm

 

Can you keep water inside a bucket if you turn it upside down? Try this experiment to see if you can keep water inside the bucket without spilling it.

It is best if you can do this experiment outside on a nice sunny day and if you happen to spill or splash the water it will feel refreshing and not make a mess inside.

1.  Fill the bucket three quarters of the way with water.
2. Take the bucket by the handle and start spinning it around at your side from the ground, up to the sky, turning your arm behind you as the bucket makes it way back down towards the ground. 3. Keep the speed and motion of rotation the same.

What happens? Does the water stay in the bucket or does it spill out of the bucket?

If you keep the speed up and a smooth motion of the rotation going around with your arm, the water will stay inside the bucket. This is due to the force of gravity pulling the water towards the center of the earth as the bucket heads down and as the bucket of water goes up towards the sky the motion (or direction) of the water is forced to stay inside the bucket (the wall and bottom) as it can not escape from inside the bucket.

 

Want to know about the heart?

What is the heart?

The heart is the organ that supplies blood and oxygen to all parts of the body. It is about the size of a clenched fist, weighs about 10.5 ounces and is shaped like a cone. The heart is located in the chest cavity behind the breastbone, between the lungs and upper to the membrane. The heart is surrounded by a fluid filled sack called the pericardium. Blood is pumped away from the heart through arteries and returns to the heart through veins. The main artery of the body is the aorta and the main veins of the body are the vena-cavae.

FAST FACTS:

The heart beats approximately 72 times per minute.

The pumping of the heart is called the Cardiac Cycle, which occurs 72 times per minute. This means that the cycle lasts for eight-tenths of a second. During this cycle the entire heart actually rests for about four-tenths of a second!

 

Brain Power!

 

 

 ALL ABOUT TREES

 

 

 

Top Ten Amazing Plants!

 

The amazing

B  O  D  Y

Highways of blood. A burly body guard of an immune system. Bones consistently rebuilding. You won’t believe how brilliantly designed you are.

You had about 20,000 thoughts. Picture 100 billion neurons (or brain cells), which each fire (talk to each other) five to fifty times a second on average. The impulses can travel as fast as 435km/h. This is what allows you to see an object and immediately identify that 1) it’s a cat, 2) it’s orange, 3) it reminds you of Garfield, 4) you like that comic.

You didn’t overheat or freeze. Your inner thermostat, located in the hypothalamus (a central area on the underside of the brain, controlling involuntary functions such as body temperature and the release of hormones), is an engineering marvel. A change of as little as one degree triggers your body to make lifesaving adjustments. When your temperature gets too high, blood vessels in your skin expand to release heat. When it drops, they tighten and your sweat glands shut down. Once your core temperature falls to around 36ºC, you start shivering as a way to produce heat.

Your heart beats anywhere from 60 to 100 times per minute. Imagine doing sit-ups at that pace! That’s about 100,000 times a day – and up to3 billion times in the average person’s life. What’s also very impressive about the heart is its ability to adapt to our lifestyles. During a vigorous workout, more than 70% of the heart’s output fuels your working muscles, for example, compared with just 20% while you are less active. You have about 161,000km of various blood vessels, laid end to end, and your heart pumps about 7570 litres of blood through them every day.

You breathed 25,000 times – without trying. If you had to consciously choose to breathe that often, you’d never get anything else done. Or be able to sleep. So thank your brain stem for making the habit of breathing automatic. Curious why you need to inhale and exhale so often? Well, humans have a very high metabolism; at rest, you demand about 250ml of oxygen each minute. And your lungs are perfectly designed to handle these truckloads of oxygen. They contain about 300 million microscopic air sacs called alveoli, which provide the surface area of 70m²  to 100m² ( roughly the size of half a tennis court) to bring in oxygen into the body while releasing carbon dioxide.

The muscles that help focus your eyes moved about 100,000 times. That’s a workout equivalent to an 80km walk.

You also blinked about 15 times a minute, or  almost 15,000 times while you were awake. You do this spontaneously to protect your eyes and clean away dirt. Even cooler: your brain doesn’t let you miss out while you blink – it fills in missing information so you never realise your eyes were closed.

You produce about 1.5 litres of saliva. Yes, that’s a lot of spit, but saliva is one of the body’s most underappreciated fluids. Without it, you wouldn’t be able to taste or swallow food. Or form words. Saliva is also a potent germ fighter: it’s enzymes clean your mouth and prevent tooth decay and infections. No wonder animals lick their wounds.

You made up to three million red blood cells each second. They perform one of blood’s most important roles: delivering precious oxygen to all our bodies cells. A single drop of blood contains millions of these guys, which get their scarlet shade from the protein haemoglobin (a protein that carries oxygen from the lungs to all parts of the body).

You got cut but didn’t bleed out or get a systemic infection. Next time you get a scrape, think about this: after some bleeding, which helps clean the wound, your body stops blood flow by forming a clot. If bacteria enter through the break in the skin, white blood cells quickly arrive to destroy them. Mast cells from your immune system release histamine, a chemical that increases blood flow to the place (it also makes this area red and swollen). This leads other cells to begin battle with the bacteria. It’s a magical sequence that helps save your life whenever you get cut.

The lining of your stomach regenerated about 25% of itself. Your stomach is home to a powerful fluid: hydrochloric acid, which helps break down food in much the same way that laundry detergent cleans stains. It’s so potent (strong enough to dissolve the metal zinc) that your stomach lining regenerates itself every four to five days so the acid doesn’t injure it.

You had dozens and dozens of chances to choke to death – but you didn’t. The back of your mouth displays an impressive feat of life guarding every time you eat or drink food or liquids. As you prepare to swallow, your soft palate comes to cover your nasal cavity (so you don’t squirt sauce out your nose) and your epiglottis (a flap of cartilage behind the root of the tongue, which is depressed during swallowing to cover the opening of the windpipe) covers your trachea (so food doesn’t go down your lungs.) To appreciate the art of swallowing, watch a baby being spoon fed a jar of mashed carrots. He’ll push the food out with his tongue because he is still learning how to perfect the swallowing reflex, without which he would likely die.

Your kidneys cleaned and recirculated almost 200 litres of blood. That’s over three times as much as a medium size car’s fuel tank would hold. To fully appreciate the wonder of the kidneys, which form the most high-tech filtration system you’ll ever encounter, all you have to do is look at someone on dialysis due to poor kidney function. People need a machine about the size of a mini fridge to filter their blood, adjust electrolyte levels, and get rid of waste, while your body accomplishes this without any fanfare using two small organs, each about the size of a computer mouse. Your kidneys also help maintain the proper level of hydration.

You regenerated about 0.03% of your skeleton. Your bones, as strong as steel but as light as aluminium – aren’t just some chalky-white lifeless scaffold; they are living tissues with blood vessels and nerves. They are constantly repairing and rebuilding – about 10% of your adult skeleton is replaced each year. Your bones are also a good example of ‘use it or lose it’: the bones of someone with a broken leg who is immobile for a few weeks will literally shrink during that time, but they will bulk up once the person starts bearing weight and exercising again.

Your feet produced up to 500ml of sweat. No wonder your shoes and socks smell less than fresh. That sounds like a lot, but you’ll want to cut you feet a break when you consider how much work they do. If a healthy person takes 8000 to 10,000 steps a day, that’s equal to walking the circumference of the Earth four times by the age 70!

Your skin shed about 50 million dead cells. That’s about 30,000 to 40,000 a minute. You may have heard that your skin is your body’s largest organ, and because it serves so many important functions, the scaffolding is always up, so to speak. Just 2.5cm² of skin has 650 sweat glands, 6m of blood vessels, 60,000 pigment cells, and more than 1000 nerve endings.

You may have fought cancer. Your body has trillions of cells. If a transformation occurs in the DNA of any, it can create cancer cells, which divide uncontrollably and can clump together to form tumours. When you consider how many cells split each minute – and each time a cell divides, it has to copy 30,000 genes – it’s a wonder we don’t get cancer all the time. The reason we don’t: the body’s incredible system to catch errors. When a cell divides, proofreading enzymes fix any DNA mistakes. If the proof-readers don’t work, the cell itself can detect that it’s ‘broken’ and commit suicide. It says, “I’m about to become cancerous, so I’ll kill myself to save the body”.