Transcript Newton`s Law Complete Unit

Lottery #3
WarmUp
• The size of the gravitational force between
two objects depends on their ____.
– A. frictional forces
– B. inertia
C. masses and the distance between them speed
and direction
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Newton’s 3 Laws
Newton’s First Law
Vocab:
Net Force
Force: Push or pull
Short: Law of Inertia
Long: An object in motion stays in motion, an object at rest
stays at rest unless acted on by a outside force
Example: While in a car you move at the speed of the
car(80mph)… when the car stops you continue(80
mph) until you hit another object(windshield)
More examples:
1.Earth’s Rotation and Orbit
2.Flying off a bike
3.Stuff flying off dash
Mass and Inertia
Newtons First Law
Demos
Marker in a bottle experiment
1. The marker fell in the bottle because its
inertia wanted it to fall straight down
Ping Pong ball cannon
1.
As the MASS of an object increases so
does its INERTIA
List Five objects with a lot of
INERTIA:
Ping pong ball continued in its forward motion,
can wanted to keep its rest, ping pong ball won.
Egg Spin
1. Liquidy egg is not effected when you touch the
shell so the egg is harder to start and harder to
stop
Newton’s Second Law
Newton’s Second Law Description
Newton’s Second Law Math
Short: Force= Mass x Acceleration
Example: How much force will you need to use to
push a pop machine that is 1000 kg with an
acceleration of 2 meters per second per second
Simple Rules:
1.
The greater the force that is applied to an object the
greater Acceleration it will have
F= ma
THE HARDER YOU PUSH THE MORE SOMETHING SPEEDS UP,
SLOWS DOWN, OR CHANGES DIRECTION
2. If Force is unchanged, then the greater the Mass of an object
the lower the acceleration will be
THE HEAVIER SOMETHING IS THE HARDER IT IS TO
MAKE SPEED UP, SLOW DOWN, CHANGE DIRECTION
Draw a situation
that describes the
two rules
Friction
Friction: This is
the force that
always opposes
motion.
F = 1000 x 2=
= 2000 N
If we pushed a box of kleenex ( 2kg) with the same
force ( 2000N) then what would our acceleration?
HINT: If not solving for force,
force is always on top
F=ma
A= F/m
M=F/a
A= F/M
A= 2000 N/ 2 kg
Three Types of Friction
Static Friction: Friction between two surfaces that are not moving
Rolling Friction: Friction between rolling object and a flat surface(least
amount of friction
Sliding Friction: Friction between flat surfaces where there is some
movement but force must be constantly applied
= 1000 m/s/s
Gravity
Gravity: A force of attraction between two objects
Mass
Weight: The effect of gravity on an object
Weight = Mass x gravity
Big objects attract little objects
Time
Speed (m/s)
to them:
The average skydiver
hits his terminal
velocity at a speed of
56 m/s
Terminal velocity: highest
velocity a falling object
can reach due to
force air resistance = force
gravity
When an object is in free fall
it is no longer accelerating
Acceleration
Distance
covered
1s
10
10
10
2s
20
10
30
30
10
60
4s
40
10
100
5s
50
10
150
6s
56
10
206
3s
ALL OBJECTS FALL AT
THE SAME SPEED
TOWARDS THE EARTH
BUT SOME ARE
AFFECTED MORE BY
AIR.
Why does a feather fall at a different
speed than a hammer on earth but not
on the moon?
Strength of Gravity is determined
by Mass and distance
There is no air
resistance on
the moon!
Belongs to
an object(
always the
same)
Weight
Changes
depending on
the planet or
moon
Projectile Motion
What if one object object is shot
horizontally and another is dropped?
The only force acting on either ball
is GRAVITY so they fall at the same
rate and hit the ground at the
same time
Car Crash Lesson Data Table
Groups
Impact Force
w/o barrier
Impact Force
With barrier
Change in Force
FORCE PLATE JUMP GAME
Person
Mass (kg)
Initial Force
Mass= Weight/ 9.8
This is also the
weight
Final Force(Final
F –Initial F)
Jumping Force
Jumping
Acceleration
(m/s/s)
A= Force/Mass
Mass x gravity