Transcript Motion, Forces, and Energy

Motion, Forces, and Energy
4th Grade Science
S4P3 Students will demonstrate the
relationship between the application of a force
and the resulting change in position and motion
on an object.
Motion, Forces, and Energy
• GPS: S4P3 Students will demonstrate the
relationship between the application of a force and
the resulting change in position and motion on an
object.
Motion, Forces, and Energy
•
•
•
Main Idea: Objects move when they
change their position.
A frame of reference must be established.
What frame of reference do we use in
these?:
1. Clock
2. Sunset
3. Base runner in baseball
Motion
• Motion is a change in position of an object.
• Things can move quickly or slowly.
Speed
• Speed is the distance an
object moves in a certain
amount of time.
• Distance divided by time
= D/T
• Need to know the
distance and the time to
calculate speed.
• Examples: 60miles/hour,
50 yards /second
Velocity
• Velocity is a measure of two
things: the speed an object is
moving and the direction an
object is moving
• Velocity = speed + direction
• Example: An airplane is
flying 500 mph/West
Acceleration
• Objects in motion often
change their speed.
• They can speed up or slow
down.
• They can change their
direction.
• Any change in the speed
or direction of a moving
object is called
acceleration.
How Do Forces Affect Motion?
• Forces can be a push or a
pull.
• Forces can be big or small.
• Forces make object start
moving, stop moving,
slow down, speed up, or
change direction.
• Forces are measured in
units called newtons.
• Forces game
Balanced vs. Unbalanced Forces
• If forces are balanced
there is no change in
the motion of an
object
• If forces are
unbalanced there is a
change in the motion
of an object
Gravity
• Gravity is pulling you toward Earth’s
surface.
• Gravity pulls two objects with mass
together – gravitation.
• The force of gravity between objects
depends on two things – mass and how
close together the objects are
• More mass = stronger gravitational pull
• Closer together = stronger gravitational
pull
• Gravity is everywhere in the universe
• What goes up – must come down.
Weight
• Weight is a measure of
force.
• It is the amount of gravity
acting on an object.
• How does your weight
change if you should visit
the Moon, Jupiter, Mars,
or Saturn?
• Astronauts feel weightless
when they do not feel the
pull of gravity.
• Brain Pop on Gravity
Friction
• Friction is a force that acts in the
opposite direction of motion
• It slows down objects when two
surfaces rub together
• The amount of friction depends on the
type of surface
• More friction = rough surfaces;
examples?
• Less friction = smooth surfaces;
examples
• Friction between the air and an object
is called air resistance
• Friction game
Inertia
• An object at rest will stay at
rest unless there is a force
that acts upon it.
• An object in motion will stay
in motion unless there is a
force that acts upon it.
• This is why we wear
seatbelts!
• Brain Pop – Newton’s Laws
Newton’s Laws of Physics
• Newton’s First Law: The
first law says that an object
at rest tends to stay at rest,
and an object in
motion tends to stay in
motion, with the same
direction and speed. Motion
(or lack of motion) cannot
change without an
unbalanced force acting.
Newton’s Laws of Physics
• Newton’s Second Law: The
second law says that the
acceleration of an object
produced by a net (total) force is
directly related to
the magnitude of the force, the
direction as the force, and
inversely related to the mass of
the object.
• More force = more acceleration
• More mass = less acceleration
Newton’s Laws of Physics
• Newton’s Third Law: The third
law says that for every action
(force) there is an equal and
opposite reaction (force).
• Forces are found in pairs.
• Example: Sitting in a chair your body exerts a force
downward and the chair needs
to exert an equal force upward
or the chair will collapse.
What is work?
• Work is done when a
force is used to move
an object a certain
distance.
• To do work, a force
needs to push or pull
on an object and the
object needs to move
in the direction of the
force.
Energy
• In science, energy is the
ability to do work.
• Energy is needed to apply
a force to an object to
make it move.
• Energy is needed to make
matter change.
• Energy is what makes the
motion and change
happen.
Forms of Energy
Energy Can Change Form
• Energy does not always stay
in one form.
• Energy can change form.
• Energy can be passed from
one object to another.
• Potential energy is stored
energy – a lump of coal, an
unused battery, a piece of
candy
• Kinetic energy is energy a
moving object has – a running
person, a burning candle, a
falling ball.
Motion, Forces, and Energy
• Energy is all around us.
• Forces are used to change motion.
• Energy comes in many different forms and
can be changed from one form to another.
• Energy allows you and other objects to do
work.
• Knowing about energy can help us use it
wisely!