Transcript Projectile Motion

AGENDA 31-OCT
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Binder check today!
Notes - Projectile Motion
CW - Plotting Projectile Motion Activity &
www.stmary.ws/physics/home/animations3 to
play projectile motion Cyclops game!
HW - Happy Halloween!
Projectile Motion
Chapter 8
Mrs. Falatek
Projectile Motion
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Projectile – any object
projected by any means
that continues in motion.
Determine what the
speedometer will read for
the free falling baseball at
time = 0, 1, 2, 3, 4
Projectile Motion
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IF there were no gravity –
any object thrown
horizontally will continue in
a straight line path.
Because there is gravity
projectiles follow a curved
path called a parabola.
Parabolic Path
A ball is thrown horizontally off the cliff.
 Forces acting on the ball
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Constant horizontal motion
Accelerated vertical motion
The combination of the two
independent forces causes projectiles
to follow a parabolic path.
Parabolic Path
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Two component Forces
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Vertical (gravity)
Horizontal (throw - constant)
AGENDA 3-NOV:
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No HW to submit
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Finish Projectile Motion Activity
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HW
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Questions? Visit
http://www.physicsclassroom.com/Class/vectors/u3l2c2.html
AGENDA 5-NOV:
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Notes – Projectile Motion
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CW – Practice Vector Problems
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HW – Part 1: Projectile Motion Lab
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Determining the velocity of a projectile
Questions? Visit
http://www.physicsclassroom.com/Class/vectors/u3l2c2.html
So Far We Know…
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a projectile is any object upon which
the only constant force is gravity,
projectiles travel with a parabolic
trajectory due to the influence of
gravity,
So Far We Know…
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there are no horizontal forces acting upon
projectiles and thus no horizontal
acceleration,
the horizontal velocity of a projectile is
constant (never changing in value),
there is a vertical acceleration caused by
gravity; its value is ~10 m/s2, down,
the vertical velocity of a projectile changes
by ~10 m/s each second,
the horizontal motion of a projectile is
independent of its vertical motion.
Vector Diagrams
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represent how the
x- and ycomponents of the
velocity change
with time
length of the vector
arrows are
representative of
the magnitudes of
Note: Horizontal vector DOES NOT CHANGE!
that quantity
Calculating Displacement
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Vertical
Displacement
y = 0.5*g*t2
Horizontal
Displacement
x = vix * t
Calculating Displacement
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Anna drops a ball from rest from the top of
80-meter high cliff. How much time will it take
for the ball to reach the ground and at what
height will the ball be after each second of
motion?
A cannonball is launched horizontally from
the top of an 80-meter high cliff. How much
time will it take for the ball to reach the
ground and at what height will the ball be
after each second of travel?
AGENDA 6-NOV:
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Projectile Motion Lab
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HW –
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Part 2: Projectile Motion Lab
TEST IN ONE WEEK
AGENDA 7-NOV:
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Submit HW
No notes
CW- The Influence of Gravity on
distance traveled & Projectile motion
challenge problems
HW –
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p 130 #1-6, Review, #1-3 Exercises
Test Friday!
AGENDA 10-NOV:
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Submit HW
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Notes – Gravity and Satellites
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CW- The Force of Gravity & Exploration WS
(if time)
HW – p 130 #11, 13, 18 Review, p 113 #2, 5, 11 &
TEST TUESDAY!
Terms to know:
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Tangent – a line that touches
a circular surface at only one
point.
Tangential Velocity – velocity
whose direction is tangential
to the Earth’s surface
(parallel or in the x-direction).
Satellite – object with vx = 8
km/s. Trajectory follows
curvature of the Earth’s
surface
Newton’s Experiment:
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cannonball launched from
an elevation > Earth’s
atmosphere.
velocityx is GREAT &
trajectory becomes a circle.
Air resistance minimal,
velocityx remains the same
Object orbits Earth
indefinitely
More Terms to know:
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Ellipse – an oval-like path.
Elliptical orbit – an orbit
followed by a projectile with a
velocity-x greater than 8 km/s.
Speed of an object decreases
as it travels away from Earth
and increases as it comes
near.
Escape speed – the speed at
which a projectile can out run
the force of gravity (11.1 km/s)
Newton’s Discovery:
The Law of Universal Gravitation
 Gravity acts between all things
 Dependent on Mass and Distance
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Force of gravity INVERSELY proportional to
the square of the distance between them.
F = [ G x (m1m2) ] ÷ (d2)
Constant = G = 6.67 x 10-11 Nm2/kg2
Some ?’s for you:
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If the tangential velocity of the moon were
zero, how would the moon move?
What happens to the force of gravity
between two objects when the mass of one
body is doubled?
How does the force of gravity between the
earth and a rocket change as the distance
between them is doubled?
Some ?’s for you:
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What other word do we use to describe the
quantity achieved when m1 is your mass, m2
is the Earth’s mass, and d is the earth’s
radius?
What must be true in order for a satellite to
stay in orbit?
AGENDA 11-NOV:
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Notes – Gravity and Satellites
CW- Newton’s Law of Universal
Gravitation
HW – p 115 Problems #1-7 & 9 p 132
Problem #1
AGENDA 12-NOV:
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Submit HW
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Review
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HW – STUDY!
AGENDA 13-NOV:
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CW – Review Packet
HW – Study!!! Test Tomorrow! PJAS #5
Due 11/21!
AGENDA ?-JAN:
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Review big ideas in Projectile Motion &
Gravity
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CW – Projectile Motion Review
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HW
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Finish Projectile Motion Review – STUDY!
Organize Binder
QPA Thursday!!!!!
Projectile Motion
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Describe for a projectile the changes in
the vertical and horizontal components
of its velocity.
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Vertical component changes at a rate of
(-) 9.8 m/s2 due to gravity.
Horizontal component DOES NOT change.
Projectile Motion
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Calculate time or distance traveled by
an object in free-fall.
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Vertical component use dy = ½ a x t2.
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Horizontal component use dx = vi x t
Projectile Motion
Show the connection between a fast-moving
projectile and an Earth satellite.
 cannonball launched from an elevation >
Earth’s atmosphere.
 velocityx is GREAT
 trajectory becomes a circle.
 Air resistance minimal
 velocityx remains the same
 Object orbits Earth indefinitely
Projectile Motion
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Describe how the speed of a satellite
changes for different portions of an
elliptical orbit.
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Circular orbit – constant speed
Elliptical orbit – changing speed
Describe what it is meant by escape
speed.
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The horizontal speed at which an object
will not become a satellite
Gravity
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State Newton’s law of universal
gravitation.
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Gravity acts between all things
Dependent on Mass and Distance
F = [ G x (m1m2) ] ÷ (d2)
Constant = G = 6.67 x 10-11 Nm2/kg2
Projectile Motion
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Describe the how the force of gravity
changes with …
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Distance – as distance increases, force
decreases by change in distance
squared! INVERSE RELATIONSHIP
Mass – as mass increases, force changes
directly by change in mass of object(s).
Some ?’s for you:
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If the tangential velocity of the moon were
zero, how would the moon move?
What happens to the force of gravity
between two objects when the mass of one
body is doubled?
How does the force of gravity between the
earth and a rocket change as the distance
between them is doubled?
Some ?’s for you:
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
What other word do we use to describe the
quantity achieved when m1 is your mass, m2
is the Earth’s mass, and d is the earth’s
radius?
What must be true in order for a satellite to
stay in orbit?