Transcript Force and motion

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Motion- a change in position, measured by
distance and time.
◦ When motion is changed it is called applied force.
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Force- an external agent that causes the
motion to move by energy, usually in a
push/pull manner.
Speed- distance traveled by a moving object
per unit of time (only gives distance and time)
◦ Speed = Distance/Time
S=d/t
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Velocity- rate (how fast) a change in position
occurs
 Accounts for distance, time, and direction of travel.
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Acceleration- the increase of velocity (speed)
and how it changes
 Vector- magnitude (how far) and direction (from
point A to point B)
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Deceleration- the decrease in velocity (speed)
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A = Vf - Vi/t
f= Final Velocity - Starting Velocity divided by
the time to change the velocity.
i=Intial Velocity over time
A = m/s2, V = m/s, t = s
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An English physicist, mathematician, and
astronomer
Changed our view of the universe with his three
laws of motion
Inertia- tendency of an object resist changes in it’s
state of motion.
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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 on by an unbalanced force.
A moving
vehicle and a
sitting cup of
liquid.
A seatbelt
strapped
to a
passenger
in a
moving
car.
This law is best explained with the
equation:
Force = Mass x Acceleration
 Acceleration is always in the direction
of the unbalanced force.
 The units of force are Newtons.
1 Newton = 1 kg x 1 m/s/s (m/s2)
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For every action, there is an equal
and opposite reaction (forces always
act in pairs).
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While driving down the road, a firefly strikes
the windshield of a bus and makes a quite
obvious mess in front of the face of the driver.
This is a clear case of Newton's third law of
motion. The firefly hit the bus and the bus hits
the firefly. Which of the two forces is greater:
the force on the firefly or the force on the bus?
Which law is this?
Answer: They have equal force, the mass of the
bug is smaller therefore it cannot withstand the
collision.
Newton’s 3rd Law of Motion
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1. What is the formula for speed?
Solve the following problem using the
formula for speed:
In a track meet Chase threw a javeline 126m
through the air. While in flight, the javeline
traveled at an average speed of 9.0m/s. How
long did the javeline remain in the air?
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Free Fall - an object falling under the
influence of gravity.
◦ Near the surface of the earth, all objects
are accelerated by gravity at a rate of 9.8
m/s2.
Friction - a force that opposes motion
(important)
Gravity- force of attraction between all
objects
◦ Gravity is the weakest of the known natural
forces, only becoming obvious when
massive objects like planets and stars are
involved
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Balanced Force- do not cause a change in
motion, they are equal in size and opposite
in direction.
Unbalanced Force-causes motion and are
not opposite or equal.
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Momentum- quantity of motion an object
has
◦ p=momentum
◦ m=mass
◦ v=velocity
p = m • v
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Actions and Reactions:
◦ Equal magnitude and opposite direction
 i.e. club and a golfball