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

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.

Average Velocity

More Examples

Velocity Average velocity Instantaneous velocity Velocity vs. Speed?

Instantaneous Velocity

Acceleration Average acceleration Instantaneous acceleration

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?

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?

Motion Diagrams See Wiley Plus Concept Simulation 1D constant acceleration Difference between constant acceleration and constant velocity

What if acceleration is known?

Memory Aid

Constant Acceleration

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.

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.

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 person’s hand. Example Problem 4

The Graphs

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?

Homework Wiley Plus Chap 2