Transcript Forces and Motion

Forces and Motion
By: Mr. Hunter
Motion
What do you think it means to be in
motion? How can we tell if something is in
motion?

Motion

Motion: a change in position, measured by
distance and time.
Motion

Frame of reference: the point from which
movement is determined.
To measure movement, some point must be
considered as _____ .
_____ is the most common frame of reference
Speed
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Speed: the distance traveled by a moving
object per unit of time
To calculate speed, use the equation
Speed = distance / time
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Speed only gives distance and time!
Average Speed
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Average speed: the speed of moving objects
is not always constant
Average speed = total
distance / total time
Average Speed
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1. What is your average speed if you take 0.5h
to jog 4,000 m?
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2. If the average speed of a car is 110 km/hr,
how long will it take the car to travel 715 km?
Graphing Average Speed
Velocity

Velocity is speed in a given direction.
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Velocity gives distance, time, and the
direction of travel.

Velocity changes by changing direction or
changing speed!
Velocity
 Velocity
= distance/time
(direction is stated in the
answer)
Speed/Velocity Problems
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1. What is the speed of a rocket that travels
9000 meters in 12.12 seconds?
2. What is the speed of a jet plane that travels
528 meters in 4 seconds?
3. A child is riding on a wagon. The wagon
goes out of control at 2 m/s! The child panics
and scoots backwards at 0.2 m/s! What is the
velocity of the wagon? What is the velocity of
the child?
Speed/Velocity Problems
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4. The space shuttle Endeavor is launched to altitude
of 500 km above the surface of the earth. The shuttle
travels at an average rate of 700 m/s. How long will
it take for Endeavor to reach its orbit?
5. How long will your trip take (in hours) if you
travel 350 km at an average speed of 80 km/hr?
7. What is the speed of a walking person in m/s if the
person travels 1000 m in 20 minutes? If the person
walks south on a northbound train traveling 20 m/s,
then what is the person’s velocity?
Acceleration

A measure of the change in velocity/ rate of
change in velocity
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Acceleration = (final velocity – initial
velocity) / time
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1. Tyler K. and TJ will start out at one side of
the room and run to the other. We will
measure their distance and time (in seconds).
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2. Calculate their speed and velocity.
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3. Calculate their accelerations. Which had a
greater acceleration.
True or false?
1.
2.
3.
If you slow down on your bicycle, you
accelerate.
If you ride your bicycle at a constant speed,
you cannot accelerate.
Changing the speed and changing the
direction of your bicycle are both examples
of acceleration.
Acceleration
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1. A meteoroid changed velocity from 1.0
km/s to 1.8 km/s in 0.03 seconds. What is
the acceleration of the meteoroid?
2. The space shuttle releases a space telescope
into orbit around the earth. The
telescope goes from being stationary to
traveling at a speed of 1700 m/s in 25
seconds. What is the acceleration of the
satellite?
Acceleration
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3. A dragster in a race accelerated from stop to 60 m/s
by the time it reached the finish line. The dragster
moved in a straight line and traveled from the starting
line to the finish line in 8.0 sec. What was the
acceleration of the dragster?
1. List all of the natural and social
constraints you can think of for the
design of your balloon car.
 2. Brainstorm ideas for structures that
you can make with the materials
available to you.
 3. Draw a picture of your prototype.
Explain, in a paragraph, why you think
your design will allow your car to be the
best!
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Force
 Force:
any push or pull.
Forces give _____ to
objects.
Forces cause a _____ in
motion.

Forces are measured in _____ .
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A _____ is the combination of all
of the forces acting on an object.
Forces
Balanced vs. Unbalanced Forces
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_____ will not cause a change in the motion
of an object; they have a net force of ____ N.
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Examples of balanced forces are: 1. ______,
2. _____, 3. _____ .
Balanced vs. Unbalanced forces
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Unbalanced forces could be best described as
__________________________ .
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Examples of unbalanced forces are
___________________________ .
Force Drawing
Create a drawing that shows an
example of balanced forces. The
drawing should show the forces
acting on the object and what
happens to the object if the forces
become unbalanced.
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Forces
Forces
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You and a younger brother or sister
are at a neighborhood pool. Your
brother or sister asks why there are
signs that say “NO RUNNING!”
What would be your answer?
Force

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_____ is a force that opposes motion between
two surfaces that are in contact.
A _____ is a substance that lessens friction.
Forces
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_____ , ______ , and ______ are examples of
common lubricants.
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Therefore, it is easier to slip when there is
water on the floor because the water acts as a
______ that lessens the friction between the
bottom of your shoe and the floor.
Friction
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Two types of friction are _____ and ______ .
Friction Pros
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Walking
Writing
Driving a car
Friction Cons
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Makes movement difficult
Wastes energy
Wears things out
Friction
Write a story
that describes
what a day in
your life would
be like if there
was no friction.
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Gravity
Gravity
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Isaac Newton discovered the ______ ______
of Gravitation.

Gravity acts on any objects with mass.
Example: You and your books, pencils, paper,
etc.
Universal Gravitation Constant
G = 6.67 x 10-11 N
m2/kg2
Scientific Notation

This is the scientific notation for the standard
number, 567 000.
5.67 x 105
Scientific Notation
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Example: 6.03 x 107 = 60 300 000
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Write 6.03 X 10 -7
Multiplying with Scientific Notation
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Ex 1. Multiply (3.45 x 107) x (6.25 x 105)
 First, rewrite the problem as:
(3.45 x 6.25) x (107 x 105).
Then multiply the coefficients and add the
exponents: 21.5625 x 1012
Multiply
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3.04 X 10^6
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2.02 X 10 ^14
and
and
5.0 X 10^8
6.8 X 10^56
Dividing with Scientific Notation
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Rule for Division - When dividing with scientific
notation, divide the coefficients and subtract the
exponents. The base will remain 10.
Ex. 1 Divide 3.5 x 108 by 6.6 x 104
rewrite the problem as:
3.5 x 108
--------6.6 x 104
Divide the coefficients and subtract the exponents
to get:
0.530303 x 104
Dividing
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4.10 X 10^72
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56 X 10^5
by
by
7.0 X 10^7
8.0 X 10^ 5
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What is the force exerted by Big Ben on the
Empire State building? Assume that Big Ben
has a mass of 108 kilograms and the Empire
State building 109 kilograms. The distance
between them is about 5000 kilometers and
Big Ben is due east of the Empire State
building.
The Solution
2.67×10-7N
What is the gravitational force that the sun
exerts on the earth? The earth on the sun? In
what direction do these act? (Me = 5.98×1024
and Ms = 1.99×1030 and the earth-sun
distance is 150×109 meters).
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The Solution
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3.53×1022
Universal Law of Gravitation
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Mass and gravity have a directly proportional
relationship.
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The distance between the centers of masses of
the two objects and gravity have an inversely
proportional relationship.
Fill-In-The Blank
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Two bodies of equal mass are separated by
a distance R. If you double the distance
between them the new gravitational force
will be _______________________ .
Differentiate between Mass and
Weight.
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Weight is dependent upon the acceleration
due to gravity on a particular planet.
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For instance: g on earth is 9.8 m/s²
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The larger the planet, the _____ the
gravitational force.
Determine your weight/ how far you
could jump on other planets.
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Moon
0.17
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Mercury
0.38
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Venus
0.86
Earth
1.0
Mars
0.38
Jupiter
2.87
Saturn
1.32
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Uranus
0.93
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Neptune
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1.23
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