Motion, Forces & Machines
PowerPoint Presentation
Paige Davis
&
Andrea Edney
Core #3 – Science
Introduction
• You have just watched an short clip of the
rocket. Did you ever wonder what powered
the rocket or how fast it went?
• Both of those questions can be related to
motion , forces and mechanics.
Speed
• The speed of an object is the distance the
object travels per unit of time. Speed is a
rate which tells you the amount of
something that occurs or changes in one
unit of time.
• Speed=distance over time
• V=d/t
• Speed can be divided into two subtitles
constant speed & average speed.
Constant & Average Speed
• Constant speed is the speed that does not
change.
• Average speed is the total distance
divided by time.
Velocity
• Velocity is Speed in a given direction.
• If you know the velocity of an object you
know its speed and velocity.
• Velocity is “direction-aware”. The direction
of the velocity is simply the same as the
direction which an object is moving. If
going downward the velocity is downward.
If going upward the velocity is upward.
• V=d/t
Acceleration
• Acceleration is change in velocity divided
by the change in time
• Acceleration is final velocity (ending
speed) minus initial velocity (starting
speed) divided by change in time
• a = vf -vi / t
Momentum
• Momentum equals mass times velocity
• P=mv
Acceleration
• The acceleration of an object as produced
by a net force is directly proportional to the
magnitude of the net force, in the same
direction as the net force, and inversely
proportional to the mass of the object.
• Acceleration=force over mass
Weight & Mass
Mass is an object
that will not change
If the force of gravity
on its changes. mass is a
Useful physical property for
Describing and measuring
matter. The SI unit of mass is
Kilograms.
Weight is a measure
Of the force of gravity
On you. Weight is a
Useful measurement
Of how much matter
An object has.
Newton's 1st Law of Motion
• An object at rest tends to stay at rest and an
object in motion tends to stay in motion with the
same speed and in the same direction unless
acted upon by an unbalanced force.
• sometimes referred to as the "law of inertia."
• There are two parts one which predicts the
behavior of stationary objects and the other
which predicts the behavior of moving objects .
The two parts are summarized in the following
diagram.
Example of 1st Law of Motion
– Pendulum is a example for Newton's first law
– Once its in motion its always in motion.
– Once its at rest its always at rest.
Newton's 2nd Law of Motion
• The second law states that the acceleration of
an object is dependent upon two variables - the
net force acting upon the object and the mass of
the object.
• It explains the relation of force, mass &
acceleration.
• Force=mass x acceleration
• The net force on an object is equal to the
product of its acceleration and its mass.
Newton’s 3rd Law of Motion
• A force is a push or a pull upon an object
which results from its interaction with
another object.
• Action force and reaction force
Work, Force , Efficiency,
Mechanical Advantage , and
Power
• Work
• Exerting forces on the object than causes
the same object to move some direction
• To work you must move some distance
• Force
• Is a push or pull
• It can be divided into two subtitles
unbalanced and balanced
• Unbalanced force can cause an object to
start moving, stop moving , or change
• balanced force is equal forces on an
object will change the object motion
• Example of unbalanced force
• Mechanical advantage
A machine is a devise witch makes it easier
to do work
It changes the amount of force you have to
use, the distance you have to move, or the
duration you have to go in
• Efficiency
• The efficiency of a machine compares the
out put work is to the input work
• It is expressed in percent
• The higher the percent is the better the
efficiency
• Efficiency=output work over input work x
100%
• Power
• Is the rate witch work is done for the
amount of work done in a unit of time
• Power=work over time
• Power=force x distance over time
• Is a rate witch energy is transformed from
one object to another or one form to
another
Simple & Complex Machines
• Simple machines
• There are six basic
kinds of machines:
the inclined plane, the
wedge, the screw, the
lever, the wheel an
axle & pulley.
• Complex machines
• are two or more
simple machines
working together
• Machines of all types
make work easier by
changing the size or
direction of an applied
force.
Difference between Powered
Vehicles and Rockets
rockets and powered vehicles are both
examples of machines
Bibliography
• www.united streaming. COM
• Physical science textbook
• http://classroom.jc-schools.net/sciunits/force.htm#8