Download Motion Unit - Dickinson ISD

Motion Unit
Everyday Forces
TEK: design an experiment to test the force on an object
FEATURED SCIENTISTS: Albert Einstein, Sir Isaac Newton, Orville & Wilbur Wright
*Force: any push or pull that causes an object to move, stop, or change direction
*Friction: a force that opposes, or acts against, motion when two surfaces rub against
each other
a. A baseball player sliding into base feels a great deal
of friction happening between his pants and the
ground. He slows down and eventually stops due to
friction.
a
b. People on a sled don’t feel much friction as they slide down
hill covered with snow and ice. Since there’s not much
friction, the sled gains speed the whole way down the hill.
*Gravitation: the force that pulls all objects in the universe toward one another and holds
things to the surface of the earth
 Strength of gravitationDepends on the mass of the two objects and the distance between them
1. Two ping pong balls have a small combined mass so even though they pull on
each other, you can’t see them moving.
2. The earth and a human have a huge combined mass! That’s why the two pull so
hard on each other. They are always in contact unless acted upon by an outside
force.
The increased mass means increased gravity. If the mass is small then the gravity is less. The
further you get from earth the less you weigh.
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Motion Unit
*Buoyancy: a buoyant force is the upward push of a liquid or gas on an object.
The Laws of Motion
1st Law
An object will remain at rest,
and an object will continue
moving in a straight line at a
constant speed until an
outside force acts on it.
2nd Law
An object’s acceleration
depends on its mass and on
the size and direction of the
force acting upon it.
3rd Law
For every action, there is an
equal and opposite reaction.
*Magnetism: a force of repulsion (pushing) or attracting (pulling) between poles of
magnets
a. Like magnets repel
b. Unlike magnets attract
(opposites attract)
S
N
N
S
S
N
S
N
c. Earth is a giant magnet! The “North Pole” and the “South Pole” were named because of
their magnetism. Compasses are magnets. That’s why they’re used to tell directions!
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Motion Unit
Electromagnetism: a temporary magnet created by a flow of electric current around an
iron bar.
*Can turn it on and off by removing the power source
*Can strengthen the power of the magnet by adding more energy
*Can change the polarity of the magnet.
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Motion Unit
Energy
*Transformation of Energy: continuous changing of energy from kinetic to potential and back.
(bouncing ball)
*Law of Conservation of Energy: “Energy can neither be created nor destroyed.”
Energy can only change forms.
*Energy: the ability to cause change in matter
1. Kinetic Energy: energy of motion or energy in use
As the ball is
moving up and
down, it has
kinetic energy.

Types of kinetic energy: mechanical, thermal (heat), electric, sound, light
2. Potential Energy: energy an object has because of where it is or because of its
position
As the ball changes direction
to go up or down, it
temporarily stops. When this
happens, it has potential
energy.
Mechanical Light
Kinetic
Kinetic
Rolling car
T.V.
Thermal
Kinetic
Heater
Electrical Sound
Solar
Kinetic
Kinetic
Kinetic
Circuit
Vibrations Sun
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Chemical
potential
Photosynthesis
food
Elastic
Potential
Rubber
band