Tippecanoe HS AP PHYSICS Ch 2 Kinetics (1D Motion)
Variables needed to keep track of motion (kinetics)… Distance: How far travelled? Displacement: How far from start to finish? Time Interval: How much time? (s) Speed: How fast? (m) Velocity
Displacement vs Distance Distance (dotted line) covered is exactly how far the object travelled. Displacement (solid line) is the change in position (straight line distance) of an object from it starting location to the ending location.
Displacement Continued
Speed Speed is how far you have traveled over a period of time. Rate of distance covered. See board
Velocity Velocity is the rate of displacement Definition of Velocity Average Velocity (totals) Instantaneous Velocity
Average Velocity (non constant) The motion is non-constant velocity Green line is initial speed (tangent). The average velocity is the slope of the blue line joining two points
Acceleration Is the rate of change of velocity. It is expressed in meters per second per second or m/s2. Definition Equation
Graphing motion Displacement (position) vs Time Velocity vs Time Acceleration vs Time
Acceleration on a Displacement vs Time Graph
Both Uniform & Non-Uniform Acc. Non-Uniform Acceleration Uniform Acceleration
Uniform Acceleration (Equation 1) Restatement of the definition of acceleration.
Uniform Acceleration (Equation 1) (cont) What is the acceleration? Describe the motion.
Integral of Velocity vs Time The integral (area under curve) of a velocity vs time graph is the displacement of the object.
Integral of Velocity vs Time (cont)
Integral of Velocity vs Time
Integral of Velocity vs Time
Integral of Velocity vs Time
Uniform Acceleration & Ave Vel
Uniform Acceleration & Ave Vel
Uniform Acceleration (Equation 2) We can now solve for displacement.
Uniform Acceleration (Equation 2) (cont)
Uniform Acceleration (Equation 3) This equation is derived by substituting equation 1 (solved for time) into equation 2. This allows us to solve all of the variables if we do not know time.
Possible Accelerations on an Inclined Plane What is the acceleration if flat (horizontal)? What is the acceleration if straight up (vertical)?
Galileo Galilei 1564 - 1642 Galileo formulated the laws that govern the motion of objects in free fall Also looked at: Inclined planes Relative motion Thermometers Pendulum
Free Fall All objects will accelerate toward the center of the earth. The acceleration due to gravity at the surface of the earth is g. The value of this acceleration is 9.81 m/s2 (in the absence of air).
Disp. vs Time for Free Fall
Velocity vs Time for Free Fall
Acceleration vs Time for Free Fall
Non-symmetrical Free Fall Need to divide the motion into segments Possibilities include Upward and downward portions The symmetrical portion back to the release point and then the non-symmetrical portion
Combination Motions