Ch. 3

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Ch. 3 4Motion Forces

• V. Nonlinear Motion
• Projectile Motion
• Circular Motion
• Free-fall

2
A. Projectile Motion

• Projectile
• any object thrown in the air
• acted upon only by gravity

• follows a parabolic path called a trajectory
• has horizontal and vertical velocities

PROJECTILE MINI-LAB
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A. Projectile Motion

• Projectile Velocities

• Horizontal and vertical velocities are
  independent of each other!

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A. Projectile Motion

• Horizontal Velocity
• depends on inertia
• remains constant
• Vertical Velocity
• depends on gravity
• accelerates downward at 9.8 m/s2

5
ConcepTest

• A moving truck launches a ball vertically
  (relative to the truck). If the truck maintains
  a constant horizontal velocity after the launch,
  where will the ball land (ignore air resistance)?
• A) In front of the truck
• B) Behind the truck
• C) In the truck

• C) In the truck. The horizontal velocity of the
  ball remains constant and is unaffected by its
  vertical motion.

Animation from Multimedia Physics Studios.
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B. Circular Motion

• Centripetal Acceleration
• acceleration toward the center of a circular path
• caused by centripetal force

B-BALL DEMO PLATE DEMO
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B. Circular Motion

• On the ground...
• friction provides centripetal force

8
B. Circular Motion

• In orbit...
• gravity provides centripetal force

ROUND LAB
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B. Circular Motion

• In orbit...
• Which satellites travel faster?

10
B. Circular Motion

• Extra Credit
• Use the NASA Liftoffweb site to find
  theInternational SpaceStation (STATION)in
  the sky this weekend.
• liftoff.msfc.nasa.gov/realtime/Jpass/20/
• Write a brief description of your sighting -
  time, appearance, other observations.

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C. Free-Fall

• Free-Fall
• when an object is influenced only by the force of
  gravity
• Weightlessness
• sensation produced when an object and its
  surroundings are in free-fall
• object is not weightless!

CUP DEMO
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C. Free-Fall

• Weightlessness
• surroundings are falling at the same rate so they
  dont exert a force on the object

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C. Free-Fall
Space Shuttle Missions
Go to Space Settlement Video Library.
NASAs KC-135 - The Vomit Comet
Go to CNN.com.
Go to NASA.
14
ConcepTest 1

• TRUE or FALSE
• An astronaut on the Space Shuttle feels
  weightless because there is no gravity in space.

FALSE! There is gravity which is causing the
Shuttle to free-fall towards the Earth. She
feels weightless because shes free-falling at
the same rate.
15
ConcepTest 2

• Describe the path of a marble as it leaves the
  spiral tube shown below.

It will travel in a straight line since the tube
is no longer exerting a net force on it.