BACKGROUND:
Students have learned that there are
4 fundamental interactions that occur in our Universe. Emphasize that we
don't fully understand any of the interactions. New data may change what
is known. Physicists are in search for clues that will help understand
our very existence. Scientists have long been looking for a Grand
Unified Theory (GUT) to see if the 4 fundamental interactions are
somehow connected. Physicists feel confident that electromagnetism,
strong and weak nuclear are somehow related, but gravity acts separately
and is difficult to describe.
In the overall picture of how and why
our universe even stays together, there seems to be a link between
gravity and motion. All substances, large and small, move. This motion
could have been created through gravitational attraction of masses.
Motion is complicated, there are many different forms, for many reasons.
It is different types of motion that students will explore in lab.
It is important to get students to
think about a universe that is full of motion from the smallest atom to
the largest galaxy. Remind students that even as you sit still, we are
moving. The Earth rotates on its axis, and revolves around the Sun. Our
Solar System revolves within our galaxy and our galaxy is moving also.
Many scientists and mathematicians
speculated about motion, but it was Sir Isaac Newton, a physical
scientist and mathematician that lived in England from 1642-1727, who
formulated his 3 laws of motion. He stated very simply his 3 laws of
motion, which model what happens on Earth. You may remind students that
Newton is the person who many say discovered gravity when an apple hit
him on the head. That story is a little exaggerated, but it was Newton's
genius that unlocked many questions.
Newton's Three Laws of Motion are
called First, Second, and Third Law of Motion,
FIRST LAW:
An object that is in motion continues in motion in a straight line, at a
constant speed, unless a force acts upon it. If it is at rest, it
continues in a state of rest unless a force changes its direction. A
body that resists change in motion is called inertia.
SECOND LAW:
If an unbalanced force acts upon an object, the object will be
accelerated. (Force = mass x acceleration.) Note mass is equal to the
quantity of matter in a body and weight is due to gravity upon a body.
The greater the mass the greater the force must be for acceleration.
Gravity of the earth attracts objects in the air to the ground.
THIRD LAW:
For every action there is an equal and opposite reaction. Forces always
occur in pairs. For example pick up a book, the book is exerting down
and your arm is pushing it up.
