Transcript Forces and Motion Powerpoint 2

FORCE
AND MOTION
1.
Earth and everything on it are affected
by FORCES.
2.
A force is a PUSH OR A PULL that
causes an object to move, STOP, change
direction, SPEED up, or slow down. It is
measured in units called NEWTONS (N) after
Sir Isaac Newton.
Look closely at each picture.
What would you do with it:
push or pull?
Drag it behind the green box in
which it belongs (but make
sure some of the picture sticks
out!). Check your answers on
the next page.
3. There are three forces on
Earth every day that affect motion:
friction, MAGNETISM, and gravity.
What force is present in this picture: a push or a pull?
In which direction will the object move? Which object will move and why?
4. Friction opposes or acts AGAINST motion.

It occurs when two objects RUB against each
other.

The harder the surfaces press together, the
MORE friction
there will be.

Friction occurs in LIQUIDS and GASES as well
as
between solids.

Without friction , it would be difficult to SLOW
or
stop the motion of objects.
Video: Friction
3:09



liquids


Friction produces HEAT.
In Latin, fricare means “to RUB.”
It depends on the object's SURFACE (rough or smooth) ,
object's MASS (heavy or light), object’s SHAPE
(aerodynamic),
surface area of object (big or small) in
and gases, and how
hard an object is pushed.
Air RESISTANCE is like friction. For example, the size of a
parachute's canopy can affect how fast the parachute will
touch ground.
Objects with MORE mass will have more friction. Two
bricks will
be harder to pull than one brick.
Frictional_Forces_4[1].pp
t
What do the top arrows in each
picture represent?
What do the bottom arrows
represent?
In the top picture, which block will
move faster and why?
In the bottom picture, which block will
move faster and why?

LUBRICANTS will reduce friction. Examples
include water, GREASE, wax, and motor oil.
Without lubrication, moving parts of machines would
slow down or stop very quickly.

WHEELS or rollers can also reduce friction.
Heavier objects can be moved more easily across
the floor if on wheels.
Objects that are aerodynamic will allow less
friction. Think of rockets and how they are
shaped and cyclists and their helmets. They are
ROUNDED so they can glide through the air with
little resistance.

5. MAGNETISM is the ability of an object to push
or pull on another object that has magnetic
properties.
Magnetic force acts at a DISTANCE and cannot be
SEEN.

Magnets have poles (NORTH AND SOUTH).
 Unlike poles (N-S) ATTRACT or pull towards each
other.
Like poles (N-N or S-S) REPEL or
push away from each other.
Magnetism is greater at the
POLES.
The CLOSER the objects, the
GREATER the magnetic force.

IRON, nickel, and a few other metals are
attracted to magnets. Not all metals will be magnetic.

A magnet produces a magnetic FIELD around
itself and affects certain objects. Magnetic force
can act without TOUCHING objects.

The needle of a compass moves because of
Earth's MAGNETISM.
Magnetic_Force_2_PPT[1].
ppt
Where is the force of magnetism
the greatest in this picture and
how do you know?
6. Gravity affects objects on Earth all the time.
It hold things to the SURFACE of the Earth.
Video: What is Gravity
1:23
It pulls objects (big or small) TOWARDS each other.
Gravity is WEAKER between smaller objects and larger for
objects of greater mass.
The CLOSER objects are to each other, the greater the
force of gravity.
Video: Intro to Forces and Gravity
3:15
The gravity between Earth and anything on it is noticeable because
the MASS of Earth is so large. The pull of Earth's gravity makes any
object FALL TO THE GROUND.
As the moon goes around Earth, its gravity pulls on Earth causing
WATER in the oceans to move towards the moon. This movement is
called TIDES.
Earth's gravity also pulls on the MOON and keeps the moon moving
around Earth. In the same way, the pull of the SUN keeps Earth
moving around the sun.
Gravitational_Force_3[1].p
pt
This means that, wherever you are in the world, "down" is always
towards the ground - even though your "down" isn't the same direction
as anybody else's.
grap
h...
Which force(s) do you see present in this picture?
7.
Motion is the change of an object’s POSITION over a
period of time. It is described in terms of position, direction, and
speed.

Distance is the LENGTH traveled. It is measured in
meters (m), kilometers (km), feet (ft), or miles (mi).

Distance from the REFERENCE point changes when the
object moves.
7.
Motion is the change of an object’s POSITION over a
period of time. It is described in terms of position, direction, and
speed.

Distance is the LENGTH traveled. It is measured in
meters (m), kilometers (km), feet (ft), or miles (mi).

Distance from the REFERENCE point changes when the
object moves.

using
Direction is the PATH that an object moves and can be
determined by reading a COMPASS. It can be described
the terms north, SOUTH, east, west, RIGHT, left,
FORWARD, toward, UP, down, or with degrees.
Speed is a measure of how FAST an object is
moving. To determine speed you must know TIME
and distance traveled.

Time is how LONG it takes. It is measured
in SECONDS (sec), MINUTES (min), or HOURS
(hr).
video: Laws of Motion 17:28
Motion_5[1].ppt
8.
In order to observe motion, you must first
observe or determine an object’s POSITION, or its
place or location.

Position can be described using points on a
GRID
An object's motion depends on your FRAME of
reference (a group of objects from which you can
measure a position or motion).
1. What do the arrows represent in this picture?
2. What part of the map shows you direction?
3. What direction is the car on the left traveling? On the right?
4. What do the squares represent on this map?
Position of an object is its LOCATION relative to
another object (called the REFERENCE point).
Words that describe position include ABOVE,
below, besire, BEHIND, ahead of, as well as the
distance from the object.

An object is moving if its position CHANGES.

An object not moving is at REST.
In what direction would
you be traveling on a trip
from Chicago to St. Louis?
How would you know?
Which city is the greatest
distance from Chicago?
What direction would you
be traveling if you left
Chicago for Des Moines?
9.
Forces can be BALANCED or unbalanced.
SEVERAL forces can act on an object at the same time.
10.
Balanced forces are EQUAL in size (and
strength)and OPPOSITE in direction.
They will not change the object's MOTION or
direction.
Balanced_and_Unbalanced_Forces_6[1]
.ppt
The forces on this pinata are
balanced, because it it hanging
still.
11.
Unbalanced forces occur when one force is
GREATER than its opposite force.
Unbalanced forces change the RATE and DIRECTION
of the motion of objects.
If the object is AT REST, an unbalanced force will cause
it to move in the DIRECTION of the force.
A stronger FORCE (push or pull) will make an object
move FASTER.
The object's MOTION will change with unbalanced
forces.
They will cause an object to MOVE, stop, speed up, slow
down, or CHANGE DIRECTION.
An object will move in the direction of the GREATER
force.
If force is applied in the same direction as a moving
object, the object will SPEED UP.
If the force is applied in the opposite direction
as a moving object, the object will SLOW DOWN
OR STOP.
If the force is applied to the side of the moving
object, the object will TURN.
12. Rate if motion is the speed of an
object or how fast or slow the object is
moving.
13. An object's motion can be affected
by a change in FORCE or a change in
MASS.
If two objects with the same mass are acted on by a force, but the
force is greater for one of the objects, the one that had the greater
force applied will have the GREATER change in speed.
If equal force is applied to objects of different masses, the object
with the LESSER mass will have the greater change in speed.
It is harder to change the speed of objects with GREATER mass than
those with lesser mass.
14.
Newton’s three laws help explain the movement in space and
on EARTH.
An object will remain at REST (or in STRAIGHT line at a constant
speed) unless an outside force acts upon it. Basically, objects do not
change motion unless they are FORCED to. This is known as
INERTIA. This is why you move forward in a car when it suddenly
stops (and should always wear your SEATBELT!).
Video: Laws of Motion 17:28
04 Newton, Way Long
Ago.wma
An object's acceleration depends on the SIZE and direction of
the FORCE acting on it and the object’s MASS.
A larger force will cause MORE acceleration than a smaller
force.
Increasing the force on a moving object will cause it to SPEED
up; decreasing the force will cause it to SLOW down.
The DIRECTION of the force will cause the object to speed
up, slow down, stop, or change direction.
Mass and Weight video
2:07
The greater the mass, the GREATER the force
needed to accelerate the object.
For every action there is an equal and opposite
REACTION.
www.physicsclassroom.com
www.physicsclassroom.com
15.
Graphing an object’s motion:
TIME is usually shown on the x (HORIZONTAL) axis
Distance is usually shown on the y (VERTICAL) axis
The slope of the line will tell you if speed is FAST (high and
steep), SLOW (low and flat), or at a constant speed
(STRAIGHT line).
Remember to label BOTH axes and give your graph a TITLE!
Rate_of_motion_7[1].
ppt
intro to site
graphing game
Decide what each graph is showing
about speed:
Slow Speed?
Fast Speed?
Speed has stopped increasing?
Move the box to check your
answer(Drag the box from the far
left).
Speed has stopped increasing
Slow Speed
Fast Speed