Kinematics (Stuff moving) (stuff)
The Equations! Don’t forget these definitions! All you get on AP Equations Sheet
The area of a velocity “curve” is displacement! v Avg velocity area t
Kinematics Examples • Drag race • Avg velocity given time and disp • Avg acceleration given final v and disp • Motion Graphing • Aircraft Catapult • Draw position and acceleration given velocity
Drag Race 1. A car travels 402 .34 meters in 11.963 sec. What is its average velocity? 2. The same car reached 40.73 m/s at the end of the first 201.17 meters. What was its average acceleration?
Drag Race #1 Given: Dx= 402 .34 meters in Dt=11.963 sec. Unknown: vavg=?? Principle: Kinematics(where to look for eq’n) Picture: Equation: Simplify/Solve/Substitute
Drag Race #2 Given: vf= 40.73 m/s in Dx=201.17m Unknown: aavg=?? Principle: Kinematics(where to look for eq’n) Picture: zero Equation: Simplify/Solve/Substitute
Aircraft catapult • Navy aircraft are launched from the decks of aircraft carriers with a steam powered catapult. The graph shows the velocity of the aircraft as a function of time. Analyze the graph and draw corresponding position and acceleration graphs.
Aircraft Catapult(v) v(m/s) 50 time(s) 5
Aircraft Catapult(a) a(m/s2) 20 time(s) 5
Aircraft Catapult(x) x(m) 300 200 100 time(s) 5
Freefall • Same kinematics equations… • Just constant acceleration of a=g=9.8 m/s2 • toward earth. Do yourself a favor and call down negative.
Freefall Example • 2) A ball is given an upward velocity of 5.0 m/s, what is the maximum height it will reach? • 3) How long does it take to reach this max height?
Freefall Example • 5) A ball is thrown upward with a velocity of 4.0 m/s. How fast is it going when it hits the ground, 10 meters below where it was thrown from?
Freefall Cases • Downy • Dropping or “spiking” • Uppy • Toss up • Uppy – downy • Toss up off a ledge, object lands lower than the ledge Establish your coordinate system and be consistent with signs.
Wrap up • Givens • Unknowns • P&P • E • Time or none given • S & S & S
More examples • More example problems • Try: v0=-3.0, a=5, Dt=4, Dx=? • Try a “spike” (as in football player’s touchdown celebration) • xf=-5.0, x0=2.0, v0=-1.0, a=-9.8, Dt=?
The Equations! Don’t forget definitions