Classical Mechanics

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Classical Mechanics

• Kinematics how objects move
• Translational motion
• Rotational motion
• Vibrational motion
• Dynamics Forces and why objects move as they do
• Statics special case - forces cause no motion

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Reference Frames

• Position, distance or speed must be specified wrt
  some reference frame.
• Coordinate axis
• Position coordinate
• Displacement change in position
• final minus initial
• Displacement is a vector! Direction is from the
  initial to final position.

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Average Velocity
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More Examples
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Velocity

• Average velocity
• Instantaneous velocity

Velocity vs. Speed?
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Instantaneous Velocity
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Acceleration

• Average acceleration
• Instantaneous acceleration

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Example Problem 1

• A jogger runs in a straight line with
• an average velocity of 5.00 m/s for 4.00 min.
• an average velocity of 4.00 m/s for 3.00 min.
• What is her total displacement?
• What is her average velocity during this time?

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Example Problem 2

• A particle moves along the x-axis acording to the
  equation (x is in meters, and t is in seconds)
• What must be the units on the constants?
• What is the instantaneous velocity at t 3.0 s?
• What is the instantaneous acceleration at t 3.0
  s?
• What is the displacement between t 2.0 s and t
  3.0 s?
• What is the average velocity between t 2.0 s
  and t 3.0 s?

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Motion Diagrams
See Wiley Plus Concept Simulation 1D constant
acceleration Difference between constant
acceleration and constant velocity
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What if acceleration is known?
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Memory Aid
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Constant Acceleration
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Example Problem 3

• A car will go 0 to 87 mph in 8 sec. Assume the
  acceleration is constant.
• Find the acceleration
• Find the position after 8 sec.
• Find the velocity after 10 sec.

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Falling Objects

• Galileo at a given location on the earth and in
  the absence of air resistance, all objects fall
  with the same constant acceleration.

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Example Problem 4

• A person throws a ball upward into the air with
  an initial velocity of 15.0 m/s.
• Find
• How high it goes
• How long the ball is in the air before it comes
  back to his hand
• How much time it takes to reach maximum height
• The velocity of the ball when it returns to the
  throwers hand
• At what time the ball passes a point 8.00 m above
  the persons hand.

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The Graphs
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Deceleration

• My golf ball goes flying in to the sandtrap at
  30.0 m/s. It looks like a fried egg buried 3.00
  cm into the sand. What was the acceleration of
  the golf ball caused by the sand as it landed?

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Homework

• Wiley Plus Chap 2