Download PowerPoint Presentation - Hillsdale Public Schools

Linda L. Smith
NASA Astrophysics Educator Ambassador
• Look at the poster and identify examples of
Newton’s 1st law of motion and explain.
Figure Skater
To begin moving,
A figure skater must apply a force using her skates.
Once in motion,
She’ll continue to glide along the ice in a straight line for a long time
Unless she applies another force.
Tug of War
When each end of a rope is pulled,
the rope will move in the direction of whoever is pulling harder
whoever is applying more force.
In this case, the magnitude or strength of A (on the right)
is greater than that of B (on the left),
so the rope accelerates to the right.
Snowboarder
A snowboarder experiences a
force due to gravity which pulls
her down.
She will move
in a straight line
unless she applies
a force to the board,
changing direction.
Train
A train is a very massive object,
and therefore has a lot of inertia.
Once in motion, it is very difficult to stop,
requiring a very large force to slow it.
Jogger
A jogger experiences many forces while
running:
• Gravity
• The push of her feet,
• Friction of her shoes on the ground,
• Air resistance.
Her legs, together with the friction of
her shoes, overcomes her inertia to
propel her forward.
Car Hitting a Wall
A car rolling down a hill is being moved by the force of gravity.
When the car hits the wall, the greater inertia of the wall stops it.
But anything not attached to the car will still move forward,
So the man running after the car
will lose his coffee, his lunch, and his briefcase.
• Look at the poster and identify examples of
Newton’s 2nd law of motion and explain.
Waterfall
As the water flows over the
edge of the rocks, gravity,
which exerts a downward
force on it, causes it to
accelerate downward:
The water moves faster the
longer it falls
Throwing a Ball
When the girl throws the ball, she
is applying a force to it and
accelerating it.
As soon as she lets go,
gravity,
which also applies a force,
accelerates the ball downward.
Cube being Pulled
A heavy cube
sits on a surface.
If someone
applies a force to it
that is stronger
than the effect of gravity
and the frictional forces on it,
Then the object will accelerate.
Swinging
When a girl swings, gravity accelerates her
downward from the top of her arc.
Her inertia keeps her moving at the
bottom, and the force of the tension in
the ropes makes her move in an arc
upwards.
Gravity then pulls her down, decelerating
her until she stops, and the motion
repeats.
Swivel Chairs
The velocity of an object includes its
speed and its direction.
Acceleration is the change in velocity,
So changing the speed and/or the
direction of an object is an
acceleration.
In a swivel chair, the woman feels an
acceleration because her
direction is constantly changing as
she spins.
Baseball Player
A baseball player applies a
large force to a baseball,
accelerating it to high
velocity.
If the ball had more mass,
that same force would not
accelerate the ball to such
a high velocity.
Cars
When a driver hits the gas, the wheels apply
a force on the ground due to friction. This
force accelerates the car forward.
The brakes apply a force to the wheels, which
in turn apply a frictional force to the
ground, decelerating the car.
• Look at the poster and identify examples of
Newton’s 3rd law of motion and explain.
Rocket
A rocket works by propelling mass out
the back end at high velocity.
The action of the mass of the burning
fuel accelerating out the back end
applies an opposite reaction force to
the rocket, moving it forward.
The rocket is not simply pushing against
the ground.
This works even in the vacuum of space
Trucker and Ramp
When the man pushes the heavy box
up the ramp, he applies a force to
the box.
The box reacts by pushing back.
If the man pushes hard enough,
he can overcome
gravity and friction,
accelerating the box up the ramp.
Shopper
The woman
pushing a
shopping cart
feels an opposite
force applied by
the cart on her.
Baseball Player
When the baseball player hits
the ball with her bat,
the ball reacts by pushing
back on her.
The player feels this as a jerk
back-wards when the bat
contacts the ball.
Fish
Fish propel themselves forward
by push-in water back, behind them.
The water reacts by pushing the fish in the opposite direction,
forward.
Hand Pulling On Rope
Connected to a Weight
When the hand pulls the rope attached to the weight,
it applies a force to the weight,
The weight reacts
by applying a force in the opposite direction.
The hand feels a resistance.
Bridge
Suspension bridges are all about actions and reactions.
The roadway hangs from the vertical cables, pulling them down, and the
vertical cables react by holding the roadway up.
Soccer Player
When the boy runs up to the ball and kicks it, he applies a force to the
ball, moving it forward.
The ball reacts by pushing back against the boy, which he feels as
pressure on his foot when he kicks the ball.
Hammer and Nail
The hammer hitting the nail
applies a large force to it.
The nail reacts
by push-in back
against the hammer.
The carpenter feels this
as a jolt backwards
against his hand.
• Look at the poster and identify examples of
Newton’s law of gravitation and explain.
Solar System
All the planets in the solar system
orbit the Sun due to its gravity.
The inner planets are closer to the Sun
and feel more gravity,
so as a result they move faster.
Astronaut
An astronaut in orbit
is accelerated
by Earth’s gravity.
But without
the balancing upward force
from the ground,
she falls freely.
Sir Isaac Newton
Isaac Newton was the person
who realized that all
massive objects in the
Universe apply the force of
gravity to all other massive
objects. An apple didn’t
really fall on his head, but
he did realize that the force
causing an apple to fall is
the same as the force
causing the Moon to orbit
the Earth – The Earth’s
gravity.
Cyclist falling or girl falling
Bicyclists speeding down a
hill and falling towards the
ground are aware of
gravity.
The gravitational pull from
the Earth is what makes
the cyclist accelerate
towards the ground.
Swift Satellite
The effect of
Swift’s horizontal velocity
(from its launch rocket)
exactly cancels
the downward velocity
gained from
the acceleration
due to Earth’s gravity.
This gives Swift
its circular path
around the Earth just as the moon
orbits the Earth.