Download - St. Aidan School

Motion Chapter 9
Reference Point – is a place
or object used for comparison
to determine if something is
moving.
SI units - scientists use the
International System of Units
to describe the distance an
object moves.
Section 2
Calculating Speed
Speed = Distance/Time
Instantaneous speed - rate at
which an object is moving at
a given instant in time.
Velocity - speed in a given
direction. If you know both
the speed and direction of an
object’s motion, you know
the velocity of the object.
Calculating Slope:
Slope = Rise/Run
Rise is the vertical difference
between any two points on
the line. The run is the
horizontal difference between
the same two points.
Section 3
Acceleration - the rate at
which velocity changes (“the
process of speeding up”).
Increasing speed
Decreasing speed
Change in direction.
Increasing Speed whenever an object’s speed
increases, the object
accelerates.
Decreasing Speed - slow
down or decelerate.
Changing Direction - an
object can change direction
as well as change speed.
Calculating Acceleration
Final speed – Initial speed
Time
Chapter 10
Force - A push or pull.
Described by its strength and
by the direction in which it
acts.
Measured in (N) Newton’s
Unbalanced Forces can
cause an object to start
moving, stop moving, or
change direction.
Balanced Forces are equal
forces acting on one object in
opposite directions. It does
not change the objects
motion. (P. 336)
Section 2
Friction - the force two
surfaces exert on each other
when they rub against each
other.
There are 4 types of Friction:
1. Static Friction acts on objects that are
not moving.
2. Sliding Friction is
when two solid surfaces
slide over each
other.
3. Rolling Friction is
when an object rolls across
a surface.
4. Fluid Friction is when a
solid object moves through
a fluid.
Gravity -a force that pulls
objects toward each other.
The law of
Universal Gravitation states
that the force of gravity acts
between all objects in the
universe.
MASS and DISTANCE are
the two factors that affect
this.
Mass is a measure of the
amount of
matter in an
object.
Weight is a measure of the
gravitational force exerted on
an object.
Free Fall -when the
only force acting on
an object is gravity.
(In the absence of air,
two objects with different
masses fall at exactly the
same rate. P. 346)
*Near the surface of Earth, the
acceleration due to gravity is 9.8m/s2
Air Resistance - objects
falling through air experience
this type of fluid friction.
Projectile Motion –is the
motion of an object that is
thrown.
Section 3
Newton’s Law’s of Motion
1st Law- an object at rest will
remain at rest, and an object
moving at a constant velocity
will continue moving at a
constant velocity, unless it is
acted upon by an unbalanced
force. This is known as
Inertia (an object resistance
to change in motion.)
2nd Law - acceleration
depends on the object’s mass
and on the net force action on
the object.
Acc = Net force/mass
Sec.4
3rd Law -if one object exerts
a force on another object,
then the second object exerts
a force of equal strength in
the opposite direction on the
first object.
For every action there is an
equal but opposite reaction.
Momentum -characteristic of
a moving object that is
related to the mass and the
velocity of the object.
Momentum =
Mass x Velocity
Law of Conservation of
Momentum - in the absence
of outside forces, the total
momentum of objects that
interact does not change.
Section 5
Rockets and Satellites
A rocket can rise into the air
because it expels gases with
downward action force. It
exerts an equal but opposite
reaction force on the rocket.
A satellite is any object that
orbits another object in space.
Centripetal force – is any
type of force that causes an
object to move in a circular
path.