Showing posts with label Physics. Show all posts
Showing posts with label Physics. Show all posts

Thursday, June 20, 2013

Periodic Table


We've learned about chemical elements and atomic numbers now,
but with all these different elements and atoms, how can anyone remember it all??

To help remember all of these different things, a scientist came up with something called the periodic table.
It takes all of the different chemical elements and puts them into a picture, organized by their atomic number.
Each element has it's own short name, like Oxygen is O, Hydrogen is H, Neon is Ne.

periodic table
(from: wikipedia - periodic table)

Not all of the names match exactly like you would guess!
Like Gold is Au, Sodium is Na, and Lead is Pb.
There are some really crazy named elements too, like Darmstadtium (Ds) and Ununpentium (Uup)!

Thursday, June 13, 2013

Atomic number


We already know that atoms are super small things,
and that they have even smaller protons, neutrons and electrons in them.

We also know that chemical elements and molecules make up all the things in the world,
from the air to the water to the earth.

Each one of those chemical elements is different, because of the number of protons it has.

And the number of protons an atom or element has, we call that the atomic number.
It's different for every chemical element in the world!
atomic number
(from: wikipedia - atomic number)

For example, oxygen has 8 protons, and gold has 79.

Thursday, June 6, 2013

Chemical Elements


Chemical Elements may be kind of hard to say,
but what that means is the very simple types of atoms that make up all of the molecules
that make up everything in the world.

So for example, Oxygen is a chemical element, and so is Hydrogen.
They're both types of gases,
and they both are atoms all by themselves.

But when these atoms get stuck together, they become a molecule and turn into water!

Every type of thing on the planet is made up of these chemical elements,
from the dirt under your feet to the clouds in the sky.
chemical elements
(from: wikipedia - chemical element)

Thursday, May 30, 2013

Molecules


Remember we learned that ions are atoms with a mismatched number of protons and electrons.

When these mismatched atoms meet up with other mismatched atoms,
they can stick together to become a bunch of atoms, called a molecule.

(from: wikipedia - properties of water)

Thursday, May 23, 2013

Ions


We've learned before about atoms,
and the parts inside of them protons, neutrons and electrons

Electrons have a negative charge, and Protons have a positive charge.

If an atom has more electrons than protons or more protons than electrons,
then we call it an ion.

If we know the number of electrons and protons, we can figure out whether it is more negative or more positive.

So if an atom has 4 electrons and 2 protons, then there are 2 more electrons.
This would give the atom a negative charge of 2.
An ion with a negative charge is called an anion.

If an atom has 6 protons and 2 electrons, then there are 4 more protons.
This would give the atom a positive charge of 4.
An ion with a positive charge is called a cation.


(from: wikipedia - ion)

Thursday, May 16, 2013

Mass


We learned before about Earth's gravity and how it pulls you to the ground.

The reason it does that is because of something called mass.

Mass is sort of like how heavy something is, but also how big it is.

So a marshmallow as big as a house may be heavy enough to squash you,
but if you had a marshmallow as big as a bowling ball, the bowling ball is heavier.

A bowling ball is pretty heavy, but a bowling ball the size of a penny would be pretty light.

The two things that work together for mass are size and something called density.
Density is another big word that means something like how thick a thing is for it's size.

If something has really big size and density (like Earth) then it has really big mass.
If it is big but fluffy like a cloud, it has small mass.
If it is small but really thick density like a marble, it has small mass.
And if it is small and fluffy like a marshmallow then it has really small mass.
earth
(from: wikipedia - earth)

marshmallows
(from: wikipedia - marshmallow)

Thursday, May 9, 2013

Earth's Gravity


When you drop a ball to the ground, what makes it fall?

Gravity! Our gravity comes from our planet Earth always pulling us back toward the ground.
Gravity is a type of acceleration, and the longer we fall toward the Earth the faster we'll go.

So if you fall from an airplane, you'll start out falling slow,
then you'll go faster and faster until you pull your parachute and slow yourself down.

If you drop a ball from the sky, it will fall slow at first, then faster and faster.
gravity
(from: wikipedia - gravitation)

Thursday, May 2, 2013

Acceleration


Last time we learned how kinematics is the study of measuring how things move.
We learned about distance, time and velocity.

There's another fun thing we can measure, called acceleration.

Imagine you are in a race car at the starting line.
As soon as the race starts you are going to speed up to go as fast as you can, until you cross the finish line.

How fast were you going right before the race started?
Your velocity was zero, (0 mph) because you weren't moving.

And by the time you crossed the finish line maybe you were going super fast,
so your velocity was 100 mph.

When we want to measure how fast you sped up, that's called acceleration.
We usually use the letter a for acceleration.

We're measuring how much velocity (v) changes over time (t).
Velocity is in miles per hour (mph) or meters per second (m/s).
Time is in hours (h) or seconds (s).

So m/s / s = m/s^2, meters per second per second or meters per second squared.

It might sound funny, but that's how we measure how fast we changed from one speed to another.


(from: wikipedia - acceleration)

Thursday, April 25, 2013

Kinematics


We've learned now about measuring distance, time and velocity.

A word for the way these things work together is called kinematics,
which really just means a way to understand moving things.

Using kinematics, we can use the things we can measure in a special way,
we can use two of them to figure out the third one!

So if you drive in a car, and you know how fast you went (velocity v)
and how long it took you to get somewhere (time t)
you can figure out how far you went! (distance d)

Let's say we went 10 miles per hour (v = 10mph)
and we went for 2 hours (t = 2h)

We can figure out our distance (d) by multiplying v times t.
If you know some algebra, it looks like this:
d = v * t
d = 10mph * 2h
d = 20 miles

We can do the same thing with time, but we divide our distance by our velocity:
t = d / v

And we can get velocity if we have distance and time.
d = v * t

Fun!


(from: wikipedia - kinematics)

Thursday, April 18, 2013

Velocity


We've learned now about measuring distance and time.

Another thing we can measure is called velocity.

Velocity means speed, or how fast you are going.
It is measured by looking at how much time it takes you to go a distance.
So if you run for 20 meters and it takes you 10 seconds,
then you would say that your velocity was 20 meters per 10 seconds.

If you know your division, you can do 20 / 10 = 2
and then say your velocity was 2 meters per 1 second.

Sometimes we use just one letter for time and distance,
m = meters
s = seconds

So you could write 2 meters per 1 second as 2 m/s

You may also have seen the letters mph before,
that means you are measuring velocity in miles per hour,
and saying how many miles you can go in one hour at the speed you are going.


(from: wikipedia - velocity)

Thursday, April 11, 2013

Time


Last time we learned about measuring distance.

Another thing we can measure is called time.

We can look at a clock to see what time it is,
and we can also use the clock to count how much time has passed.

So if you get in the car and drive to Gramma's house,
if it takes 30 minutes then that is the time measured.

Time is usually measured in seconds, and there are 60 seconds in each minute.
So if you know your math, you can take 30 times 60 = 18,000 seconds.


(from: wikipedia - clock)

Thursday, April 4, 2013

Distance


Let's talk about measuring things!

First we can learn about distance.

That means how far it is from one place to the next.
So if you drive in your car for 10 miles, then the distance is 10 miles.

(from: wikipedia - taxicab geometry)

You can also measure distances in meters.
A meter is a little bigger than three feet long.

Thursday, March 28, 2013

Solid, Liquid, Gas


Have you ever gone sledding in the snow?
What about swimming in a pool?
Have you ever seen water boil on a stove?
What about a bright neon sign for a store?

If so, then you've seen the four types of matter in our world:
solid, liquid, gas and plasma
states of matter
(from: wikipedia - states of matter)

We see water all the time in three of the four types.
An ice cube is water when it's solid, and the steam that rises from boiling water is actually the water turning into a gas.
There are lots of types of solids made from things other than water,
like the dirt you walk on, or the chair you sit in.

Solids can turn to liquids when they get hotter, like lava is actually rock as a liquid!

Sometimes gases are really hot like steam from water,
but sometimes gases are just normal temperature like the air we breathe.

Plasma is what happens when a gas gets really hot, and when the parts of the gas get really full of energy, and whenever you see a bright neon sign, it's filled with plasma!
neon
(from: wikipedia - neon sign)

Thursday, February 14, 2013

Neutrons Protons & Electrons


We learned before about how small atoms are,
but there are even things smaller that that!

An atom is really made up of two parts.
The nucleus in the middle, and the electrons that spin around the nucleus.
atom
(from: wikipedia - atom)


The nucleus can be made up of two types of things, protons and neutrons.

Remember we've talked about positive and negative?

The electrons have negative charges, the protons have positive charges,
and the neutrons have no charge at all.

Thursday, February 7, 2013

Atom


What's the smallest thing you can think of?
A grain of sand?
A drop of water?

Well even smaller than any of those is something called an atom.

An atom is so small, that in one single grain of sand there aren't just millions,
billions or trillions of atoms, but quadrillions or quintillions of them!

A quintillion is a 1 with 18 zeroes after it: 1,000,000,000,000,000,000

Atoms are the building blocks of our world, they make up every part of our bodies,
and every thing around us from the ground we stand on to the air we breathe.


(from: wikipedia - atom)

Thursday, January 10, 2013

ROY G BIV


Remember we learned before about measuring waves using wavelength.
wavelength
(from: wikipedia sine)


And we learned that how often something happens in a given amount of time is called a frequency.
frequency
(from: wikipedia - frequency)

Well did you know that the colors of the rainbow are all different because of their wavelength and frequency?

For example, the color red has a very long wavelength, and a very low frequency.
But the color violet has a very short wavelength, and a very high frequency.

That's why the colors of the rainbow are in the order they are,
and why we put them in the order of ROY G BIV.

Red is the longest wavelength and lowest frequency.
Violet is the shortest wavelength and highest frequency.
Green is right in the middle.

Sometimes it's easier to understand by looking,
so here's a good picture that helps show how the different colors have different wavelengths and frequencies:
color waves

Thursday, January 3, 2013

Frequency


Frequency means the number of times that something happens during a certain length of time.

So for example, if you clap your hands 3 times,
then 3 is the number of times

If you count out 10 seconds,
that is the length of time.

If you clap your hands 3 times while you count out 10 seconds,
then 3 over 10 is the frequency.

You can write it like 3/10.

If you clap your hands 7 times in that 10 seconds, that's 7/10, which is a higher frequency
If you clap your hands just 1 time in that 10 seconds, that's 1/10, which is a lower frequency

We can use frequency to measure lots of things from music to heart beats to airplanes!
frequency
(from: wikipedia - frequency)

Sometimes we also use the word occurrences instead of saying number of times.

Thursday, December 27, 2012

Waves and wavelength


If you are standing in the water in the ocean or a big lake,
you can watch a wave going by you, something like this:
water wave
(from: wikipedia - wave)

If you stood in one place and watched a lot of waves going by, it might look something like this:
harmonic wave

And if you took a picture of a wave while it was standing still it might look like this:
sine wave
(from: wikipedia sine)

If you measured the distance from the start of the up wave, to the end of the down wave that is called the wavelength.

Thursday, December 20, 2012

Light Year


We know that a cheetah can run 75 miles per hour.

And the speed of sound is 760 miles per hour.
Only super fast jet planes can go faster than that.

And even faster is the speed of light, 670 million miles per hour!
That's 670,000,000 miles per hour, way faster than a cheetah or even the fastest jet plane ever made.

If you could travel as fast as the speed of light and you went that fast for a whole year (365 days)
then the distance you traveled is called a light year.

A light year is a very very long distance.

To get some idea of how far it is, if a cheetah ran as fast as it could for a whole year,
it could go all the way to the moon and back.

If a jet plane went as fast as the speed of sound for a whole year,
it could make it to the moon and back 11 times,
but still couldn't reach the planet Mars or our Sun.

But if you went the speed of light for a whole year,
you could go around the earth 277 million times.
That's 277,000,000, look at all those zeroes!

You could go to the planet Mars and back 98,000 times,
to the sun and back 35,000 times.

The farthest planet in our solar system is Neptune,
and you could even go to Neptune and back 1,000 times.

So the speed of light is super fast, and travelling that fast for a year is a super crazy big long distance!

light year
(from: wikipedia - light-year)

Thursday, December 13, 2012

Speed of light


Just like the speed of sound is very fast, the speed of light is even faster!
The speed of sound is 760 miles per hour.

The speed of light is over 670 MILLION miles per hour!

So when you turn on that flashlight, the light goes out from the light bulb so fast that no boat, car or airplane can go faster.

When the sun shines, it is very far away, but it takes eight minutes for a ray of sunshine to hit earth going at the speed of light!

speed of light
(from: wikipedia - speed of light)