they push and they pull.
They make unusual sounds and and they make
machines work. They help keep planets in orbit around
stars and help your grocery list
stick to the refrigerator. They are
forces the things that keep our world in motion
forces air constantly pushing and pulling
and pushing and pulling. Does it
matter? Of course it does, because
science matters.
Welcome to science matters. I'm Mike Moscatiello. Take a look
around in. You'll see things that look like they're moving and things
that look like they're not. Whether or not something appears to be moving
is often a matter of perspective, but even more
so. It's a matter of the forces acting on it.
There are all kinds of forces in nature that influenced the way things move or
don't move. Forces push and pull on things in all
different directions, setting them in motion or
stopping motion or changing motion.
We commonly deal with contact forces thes air forces
that happen when two surfaces touch one another. They come in
contact. Sometimes an object moves due to
contact forces, and sometimes it doesn't.
That's because in order for one thing, to force another into motion and
has to overcome friction, a kind of resistance that
occurs when two surfaces touch. Friction can interfere
with our ability to do something, but very
often will use friction to help us. Whether you
travel on a bicycle wagon or the fastest
planes or cars, friction protects
you, and your safety depends upon
breaks, which applied friction for stopping.
We use forces such as contact forces to make things start moving,
stop moving, speed up,
slow down, change directions
and stay in place. This phenomenon
of force is changing. The motion of objects was described over 300
years ago by a gentleman named Isaac Newton.
Newton was a mathematician and scientist who developed various
laws dealing with the motion of objects. His
first law of motion had to do with objects, tendency to
stay put or continue moving, depending on the kinds of
forces affecting it. For instance, the guy sitting
here asleep on the job is at rest. He's
not moving anywhere,
and it doesn't look as if that's going to change anytime soon.
On the other hand, if we track the movement of the moon from day to
day, month to month and year to year, we find
that it's in continuous motion with no signs of slowing down.
Both of these things Sleepy Guy and the movie have what
Newton called inertia or resistance to a
change in motion, even if it happens to be no
movement. Newton's first law states that an object at
rest will remain at rest unless acted on by some
outside force, a push or a pope. It
also states that an object in motion will remain in
constant motion unless a force causes it to change.
In science, any change in the motion of an object is called
acceleration. It doesn't matter if the object is speeding up,
slowing down Ford changing
directions. It's all acceleration.
Outside the room of science, most people think of acceleration
simply a speeding up for going faster. That is
one way of accelerating. But in science, if the
driver of the vehicle slows down,
crashes into something or turns the wheels
to move in a new direction, it's all acceleration because the
inertia of the vehicle changes.
When forces accelerate things and get them moving, it's possible to measure how
fast they're going. We do this by calculating speed
to find an object speed you need to know the distance. It travels over a
given period of time. If a vehicle travels on a
straight path for 50 miles without going any
faster or slower for one hour, the speed of the
vehicle or any point trip is a constant 50 miles per
hour. If we know what direction the cars traveling like
north, south, east or west, that instead of speed,
we call the measurement velocity. But what was
the acceleration during the trip? Well, since nothing
about the cars motion changed, no speeding up, no slowing
down, no changing direction, there was no
acceleration. Now this is not what normally occurs.
Usually when someone is driving, there's always some acceleration going on,
speeding up, slowing down
and changing directions that turns or curves in the road.
Because of this, we often choose to calculate average, spoon
or average velocity for the distance. Something travels.
If we take the same vehicle that previously traveled the 50
miles, find that it's gone 70 miles in two hours.
We divide to find the beagles. Average speed or velocity.
70 miles divided by two hours, gives an average of 35 miles
per hour. This doesn't mean that the vehicle actually traveled
35 miles during each hour of the trip, and it also
doesn't mean it went 35 miles per hour the whole time. It's an
average speed that includes all the speeding up, slowing down,
stopping, starting in changing directions that occurred during the trip.
It all happens because pushing and pulling forces set
things in motion.
Hi, I'm Melissa's daughter. I coordinate the educational programs
here at Extreme in your party at Extreme and Dark Harding we
try. Thio introduced various things that science behind driving.
We introduce mo mentum tires and pressure,
inertia, friction and speed, displacement and
velocity. We have go carts. Here they go up to speeds of
35 to 45 miles per hour. If you didn't know,
racing is actually a science experiment in itself. There's a lot of science
behind racing. Science of speed. The physics of the racing
way have a lot of NASCAR drivers that are actually coming here to extreme
indoor carding and learning how to drive for the first time. And if you ever
had the chance to experience go kart racing, whether it be an extreme enter
carting or any go kart track. You'll get to feel the science involves
the pushing and pulling of forces. That's all kinds of things in
motion. We live in a very physical world where there's
normally more than one kind of force acting on various objects at the
same time. Usually, movement is the result
of combinations of forces acting on the same thing, but
in different ways.
When you apply a force to something and it moves, you give it mo
mentum by overcoming the objects inertia.
Momentum is a product of mass and velocity, more
mass or velocity and object has the more momentum it will have.
Isaac Newton's second Law of Motion came in the form of an
equation, he said. That force equals
mass times, acceleration forces.
The amount of pushing and pulling
mass is the size of the object being pushed or pulled.
And acceleration is the measure of how the pushing and pulling Evan
optic changes the way it moves. Knowing
some basic principles of math, this equation can tell us a lot
if we substitute numbers for force mass and acceleration like 20
equals four times five, we see a balanced equation
because 20 equals four Times five. But if we
change any of the numbers, say the four into a two,
then the 20 changes to 10 in order to keep the equation balanced.
If we change the 10 into 1/3 even way might end up with
six times five or two times 15 or any
other combination of numbers that keep the equation balanced. That's
why it's called in equation. Sides have to stay.
What is this basic math have to do with Newton and the motion of objects?
While it tells us a whole lot about Newton's second law, it
tells us that as you increase the amount of force, you can
move more mass or have greater
acceleration or a combination of the two.
The equation also tells us that if you increase the mass of
something, you have to use more force to move it.
Or if you want greater acceleration, you also have to use more force.
General idea is that force mass and acceleration are
interconnected. What's most important about Newton's second
law is understanding that there's a relationship between the amount of force
to use and objects mass
and how you're able to accelerate motion a
strange fact about forces pushing and pulling on things is that
every object pushes and pulls right back. It's
like when you lean against a wall, you can feel the pressure of the wall
pushing back on your hands. The walls. Inertia causes
it to resist any movement. It pushes back on your
hand with an equal balanced force, so neither you
nor the wall budge. But if the wall had less
inertia, well, you
get the picture. Motion happens when
astronauts trained a weightless environment before heading into space. They
have to get used to this. When they push on something, it
pushes right back with equal force, and it can send them in the opposite
direction. The pushing action one direction creates a
pushing reaction in the opposite direction. This
action and reaction of forces is described in Isaac Newton's
third Law of Motion. Action and reaction
is what helps rockets take off the action of burning
fuel. Pushing with great force in one direction creates a
reactive force in the opposite direction. This gives enough push
to move the very heavy load of the rocket on a
smaller scale. It's the same reason balloons fly around when the year
is let out on ley rockets do with much greater
control. Usually,
Newton's laws help to explain the forces at work, controlling the movement
of everything understanding forces and the effects they have
on objects helps us to better work,
play, build and
live within our physical world.
When a force causes something to move, it always happens because of
pushing more pulling. It's easy to see how this motion
happens in many cases, but not in every case. In
fact, there are some forces that are almost impossible to see it all.
With the naked eye, though we can observe their effects
quite well. There are forces at work all around
us. We can see what makes some things move, but sometimes
it's not so easy to see the forces that push and pull on things take
magnetism. For example, magnetism is not a
contact force. Magnets pull or attract
certain kinds of materials without touching them. Often those materials
contained the element iron in some form, though, there are other
magnetic substances. We can't see what's actually doing
the pulling. When it comes to magnetism, objects seem to
magically lead to the magnet on the throne. When In truth, they're
being pulled by magnetic forces. The magnetic forces
we observe start on the atomic level. Every electrons spinning
around the nucleus of an atom generates a magnetic force.
Most substances electrons spinning different kinds of
wings, but a material said exhibit magnetic properties.
The spin and orbit of many electrons are aligned. This
alignment creates an invisible magnetic field that stretches out beyond the
magnet itself. When a strong magnet comes close to
another object, that magnetized magnetic field begins to
align electrons in the other object. This causes an
attraction, the magnet in the object attract with
a pulling force. Then that object can even
attract other objects. Now don't get the wrong
idea here. Magnets don't always pull. Magnets can
also push or repel other magnetic material,
but usually only if the other material is already magnetized.
This magnetic push happens because many magnets are die polls,
meaning to polls or ends a north pole
end in a south pole end. The opposite north and
south poles attract one another, but put two of the same ends
near each other, and they repel these air
pulling and pushing forces at work.
Another force that causes motion without contact forces is
electricity. Electricity can be static or
current static electricity is simply an accumulation of
electric. Charge is often electrons in a given space,
just like the opposite poles of a magnet. Opposite electrical charges
attract or pulled toward one another and, like charges,
push away or repelled. But instead of north and south
poles, we talk in terms of negative and positive
charges. A balloon that has a negative static
charge will attract bits of paper that have a positive charge.
But two balloons with negative charges repel one another
thes air forces at work. Pulling and pushing.
Current is the movement of electrons from one place to another.
Current electricity works on the same principle of opposites attracting.
Think about an electric sell what we commonly call a battery
one. And this label is positive with a plus sign, and the other side is
negative. We can use metal wire as a
conductor, allowing negative charges to find positive
charges in doing this rail to harness the pushing and
pulling power of electricity to run all kinds of things.
There's a relationship between magnetism and electricity. When
current runs through a wire, it aligns electrons, creating a
small magnetic field around the wire. If a piece of
insulated wire is wrapped around some iron and current electricity
is run through it, a magnetic force could be built up to create
an electro magnet. One nice feature of an
electro magnet is that it could be turned on and off.
Electricity is also used to operate. Motor is, as in the washing
machine, in the dishwasher, in the electric mixer
and in many other appliances of everyday convenient.
This basic idea is also what makes speakers and electric motors work.
Not only can the force of moving electricity create magnetism,
magnetic forces can also create electricity.
Move A magnet passed a coil of wire and it jars the electrons in the
wire around. Get those electrons moving enough and
you get current electricity. This is how electricity is created. In
generators of power plants, magnets get moved past
wires, or vice versa, and the resulting electricity
is conducted to anyone who needs to plug into it.
Magnetism and electricity are just more of the pushing and pulling
forces that helped keep our world in motion.
Over here, Over here. No,
appear. Here I am. Hi, Welcome to the
Science Matters Home Laboratory. I'm J. P. Keener. And today
I'm studying gravity. Gravity is a force, and,
as you know, forces to find is a push or a pool.
Gravity is an attractive force that pulls on everything like this
cell phone and this egg. Do you need proof?
Well, let's watch. 123
gravity pulling everything down
and redefining a dropped call. See, Galileo,
did this exact experiment well without the cell phone on the now leaning
Tower of Pisa? And this is where he asked the one very important
fundamental question how attractive I am. I
and are some things more attractive than others? Well, before I
can tell you what he concluded, let me ask you a simple question. Which
of these three animals do you find to be more attractive? This
elephant at 2000 kilograms this dog
at four kilograms or me at 70
kilograms The elephant, the dog or
me? If you said the yellow world gravity, you're
100% correct. The elephant has more mass and therefore
has more gravity. More gravity more attractive.
Everything with mass has gravity on. Everything with gravity is
attractive. I'm attractive you're attractive, this pencils
attractive. This table's attractive. Everything with mass has
gravity. So let me ask you another question. Why can't I get
this pencil to stick to my face?
The pencil has mass and gravity. I have mass and gravity,
but I can't get the pencil to stick. Why?
Because the earth has the most massive
own. It is the most attractive. It has the most
gravity. Sure, my pencil finds me to be attractive,
and I find my pencil to be attractive. But we both find the
earth to be the most attractive with the most gravity. And
wouldn't you agree? This is exactly what Galileo determined on
the Tower of Pisa when he dropped heavy things and like things, big
things and little things. They all hit the ground at the exact same
time. And how is this possible? It's on Lee
possible if the more the mass, the more the gravity
and so sure pencil. You broke my heart, but I
fully understand the Earth has more mess and more
gravity. More than mass, the more to the gravity.
That's the facts here in the science laboratory.
What goes up must come down. You've probably heard this
phrase before, but it takes a force to change the motion of any
object. So if it starts out going up, something
has to force it down. In our everyday lives. That
force is usually gravity.
Much of the way we understand gravity was expressed by Guess
who Our old pal Isaac Newton
Gravity is an attractive force exerted on and between
objects. It's a force that pulls it
doesn't matter how much mass objects around us have on Earth. Everything
falls at the same rate due to the pull of gravity, although gases in
the air because friction and can slow things down.
One interesting thing about gravity is that today we really have no
better idea about what causes it. Then when Isaac Newton was alive,
we do know that everything has gravity. You,
your dog, your bicycle,
your planet and everything that floats around in the universe
way also know that the bigger something is, the more gravity it has to
pull on things thistles. Why things weigh less on the moon than they do
on the earth. Moon has less mass than the earth, so
there's less gravity to pull on things. Wait is a measure of
how hard gravity is pulling on objects. Mass
weight can help us compare masses, but
it's not the same thing as mass. The Earth has enough
gravity to keep nearly everything on it. It even keeps the
moon from floating off into outer space. The moon is
much smaller than the Earth, but has enough gravitational pull to
cause the ocean to rise at high tide. Now,
if you really want to talk gravity, check out the sun.
Because of its size, the sun has enough gravitational pull to keep
the Earth and every other planet in our solar system revolving
around from millions of miles away. We know all this and
more about gravity, but way still don't know what
causes it and the absence of gravity. The rules
change. Newton's laws of motion don't change. But
getting around without friction created by the pull of gravity is not
quite what we're used to. Just like any other force,
Gravity sets things in motion
crew. I'm like Aguinaga from the Museum of
Discovery and Science, and this is a flight
simulator. It gets pretty close to the feeling of flying
but really flying involved, working with a lot of different
forces. One force involved in flying is
gravity. Gravity is constantly pulling objects that are in flight
down toward the earth. In a flying machine like this
helicopter isn't working properly. Gravity can bring it
down fast
to overcome gravity and airplanes. Wings shape
that helped provide lift. If you take a cross section of an airplane's
wings like this one and move their over the
top, it causes low pressure. Low pressure.
Lift the airplane up just like these ping pong balls
to make air. Move fast enough over the wings and caused lift.
You have to have thrust moves. An object for words
in airplanes, Russ is usually created by a propeller or a
powerful jet engines. Last but not least,
if you want to fly, you have to deal with dress Dr
Khan, his resistance that could slow a plane down or cause it to
move in a certain direction. In this wind generator, I
can feel the resistance caused by dress as I tilt the armed
runners up. And now flying is pretty
amazing. It's all about knowing howto work with
forces.
Sometimes when forces set things in motion, it can have
amazing effects, like pushing and pulling forces that
produce sounds. But you've got to get moving
pretty fast to hear anything at all.
Sounds are made by all kinds of things, both living
and non living. A vibration happens when
something moves back and forth over and over at a steady rate.
If it's moving with enough energy way here sound.
Under regular conditions, humans can hear sounds from objects vibrating
back and forth from about 22
20,000 times a second. The faster the
vibration, higher the pitch.
When someone bangs the end of a tuning fork, the metal ends vibrate, making
a sound at a particular frequency. The frequency tells
us how frequent or fast, the vibrations, making the sound or
happening. Every second sound frequency is measured
in Hertz. The number on this tuning fork
tells us what the frequency is, but we can also use wave form
generators to help figure it out. Sound
vibrations travel in waves of motion through matter outward
in all directions from where they start, thes waves
compress and move through all kinds of matter as pushing
and pulling forces in the vacuum of outer space.
There's no sound because There's no matter for vibrating
waves to compress and push on to travel through.
Everything is silent
once it gets moving. Sound travels quickly through
the air. It moves it over 700 miles per hour,
and water sound travels at over 3000 miles per
hour and through steel, it
moves it over 13,000 miles per hour.
Sound is just another example of how forces
can really get things moving,
pushing and pulling and pushing and pulling. It
happens all the time, from the tiniest Adams to the
biggest stars, moons and planets. Forces
are at work, People move things and
things move. People sometimes forces only pull on certain
kinds of materials, and sometimes they pull on
everything. We can see forces at work
and hear that forces are at work all
around us, and there's no stopping them. We deal with
forces like we deal with everything else. We make
them work for us. It's all in the science of
things, science that