Transcript Newton`s Laws and Motion

Newton’s Laws and
Motion
3 Laws of Motion
 1st
Law – An object at rest will stay at
rest, and an object in motion will stay
in motion at constant velocity, unless
acted upon by an unbalanced force.
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2nd Law – Force equals mass times
acceleration.
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3rd Law – For every action there is an
equal and opposite reaction.
4 Types of Friction
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There are four main types of friction:
– Sliding friction: ice skating
– Rolling friction: bowling
– Fluid friction (air or liquid): air or water
resistance
– Static friction: initial friction when moving
an object
2nd Law Formula
How much force is needed to
accelerate a 1400 kilogram car 2
meters per second/per second?
1. Write the formula
 F = m x a
2. Fill in given numbers
 F = 1400 x 2
3. Solve for the unknown
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 2800
N
2nd Law Practice
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1. What acceleration will result when a 12 N net
force is applied to a 3 kg object? A 6 kg object?
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2. A net force of 16 N causes a mass to accelerate
at a rate of 5 m/s2. Determine the mass.
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3. How much force is needed to accelerate a 66 kg
skier 1 m/sec/sec?
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4. What is the force on a 1000 kg elevator that is
falling freely at 9.8 m/sec/sec?
2nd Law Practice Answers
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1. What acceleration will result when a 12 N net force applied to a 3 kg
object?
12 N = 3 kg x 4 m/s/s
2. A net force of 16 N causes a mass to accelerate at a rate of 5 m/s2.
Determine the mass.
16 N = 3.2 kg x 5 m/s/s
3. How much force is needed to accelerate a 66 kg skier 1 m/sec/sec?
66 kg-m/sec/sec or 66 N
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4. What is the force on a 1000 kg elevator that is falling freely at 9.8
m/sec/sec?
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9800 kg-m/sec/sec or 9800 N
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ALL NOTES TO THIS POINT ARE FOR
THE QUIZ
PRINT REMAINING NOTES AS SLIDES
AS A HANDOUT TO TEACH FOR THE
TEST
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Air resistance- fluid friction acting on
an object moving through air
Acceleration- rate at which an
object’s velocity changes
Gravity- force that exists between
any two objects that have mass,
attracting or pulling them together
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Friction- force that opposes motion, or
resistance, caused when two surfaces touch
or rub together
Speed- rate at which the position of an
object changes
Inertia- tendency of a still or moving
object to resist a change in its motion
Kinetic energy- energy an object has due
to its motion
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Velocity- rate at which an object
moves in a certain direction
Mass- amount of matter in an object
Force- push or pull that acts on an
object, causing it to move, change
speed or direction, or to stop moving
Momentum- property of matter due
to its mass and velocity
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Weight- measure of the force of
gravity acting on an object
Potential energy- energy that is
stored, available as a result of an
object’s position or condition
Newton- unit of force
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Motion- the process of changing from
one position, or place, to another.
Displacement- describes both how
far an object moved from its original
position and in what direction it
moved.
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Example of displacement:
A runner follows a path through a park
and goes 3 kilometers north, turns
right, and travels 4 kilometers east.
The total distance traveled is 7
kilometers, but her final position is
only 5 kilometers northeast of her
starting point. So her displacement is
5 kilometers northeast.
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Law of conservation of momentum:
– momentum= mass x velocity
– Momentum of an object does not change
unless its mass changes, its velocity
changes, or both change
– If there is no outside force acting,
momentum will not change
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Free fall- when gravity alone is acting
on an object
– Astronauts experience this in their aircraft
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Finding speed
– Speed = distance / time
– Example: A cruise ship travels 1,000 km
in 25 hours. Their average speed is
1000/25= 40 km per hour
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Net force- the force that results from all the
combined forces acting on an object
Balanced force- forces that completely
cancel each other out
Example- You are holding a piece of pizza.
The force of gravity pulling it down is equal
to the amount of force your hand is
providing to hold it up.
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Unbalanced force-when forces act on
each other and do not cancel out
Example- The game of tug of war.
When one team pulls harder, the force
is unbalanced and the opposing team
starts to move.
Displacement example
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A robot went 20 feet south, 20 feet
west, and 20 feet north.
Average Speed Example
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Mr. Robot travels 500 feet in 2
minutes. What is his average speed?