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Matter and Motion
• All matter in the universe is in motion.
• We are in motion because we are on
Earth, and Earth is revolving around the
sun.
• The blood in our body is being circulated.
• Our heart is always beating.
Changing Position
• Before we can know
our position we must
first know that
everything is in
motion.
• The distance we have
to travel to get to a
football game is how
far away it is from our
spot. It may be 2
blocks away or 50,
this is the distance.
• The displacement
includes the distance
between the starting
and ending points.
Speed
• Speed is the
distance an object
travels in a unit of
time.
• Speed can be
calculated by
dividing distance by
time.
• The average speed is found by dividing the
total distance traveled by the total time
taken.
• Instantaneous is an objects speed at one
particular
Graphing Motion
• A distance-time graph can be used to
compare the speeds of objects.
• Ex. After one second student A travels
1.5m.
• Student B traveled 1m for the first
second.
Velocity
• The velocity of an object is the speed of
the object and the direction of its motion.
• The velocity can change if the object’s
speed changes, its direction of motion
changes, or they both change.
• Suppose a car is traveling at a speed of 40
km/h north then turns left at an intersection and
continues on with a speed of 40 km/h. The
speed of the car is constant at 40 km/h, but the
velocity changes from 40 km/h north to 40 km/h
west.
Acceleration
• Acceleration is the change in velocity
divided by the time it takes for the change
to occur.
• When we accelerate we either speed up,
slow down, or change direction.
Calculating Acceleration
• In this equation, time is the length of time
over which the motion changes.
• When we speed up the acceleration is
positive and when we slow down the
acceleration is negative.
Mass & Inertia
• Mass is the amount of matter in an object.
It also measures the quantity of matter.
• Inertia is the tendency of an object to
resist a change in its motion.
Momentum
• The momentum of an
object is a measure of
how hard it is to stop the
object, and it depends on
the object’s mass and
velocity.
• The law of conservation
of momentum states that
the total momentum of a
group of objects remain
constant unless outside
forces act on the group.
For example when a group
of bowling pins are hit by a
bowling ball the law of
conservation of momentum
falls in place. Because the
bowling pins momentum are
interrupted by the bowling
ball.
• In some collisions like in bumper cars the
cars hit each other, but as soon as they hit
they bounce off, or in football when one
player tackles the other.
Review Questions
Explain the relationship between each pair.
1.
2.
3.
4.
Speed - Velocity
Velocity - Acceleration
Velocity - Momentum
Momentum - Law of Conservation of
Momentum
5. Mass - Momentum
6. Mass - Inertia
7. Momentum - Inertia
8. Average Speed - Instantaneous Speed
9. What measures the quantity of matter?
10. How do we calculate speed?
Answers
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