PHY 101 1nd Edition Lecture 5 Outline of Last Lecture II. Velocity, SpeedA. Constant VelocityB. Varying VelocityC. Instantaneous VelocityIII. Accelerationa. Average Accelerationb. Instantaneous AccelerationChapter 2: One Dimensional Motion ContinuedIV. One Dimension Motion With Constant AccelerationV. Kinematic EquationsVI. Free Falling Objects Current Lecture- One Dimensional Motion with Constant Accelerationo Velocity changes uniformly (linear)o Example: A car has Vo = 2.0 m/s to the right and accelerates right with a constant a = 3.0 m/s a. what is the velocity at t = 10s?- V = Vo + at- V = 2.0 m/s + (3.0 m/s)(10s)- V = 32 m/s = 72 mph B. if the car comes to a stop in 3 seconds, what’s the acceleration?- 0 = 32 m/s + a(10s)- A = =10.67 m/s2o Position changes quadratically with time for constant accelerationo Example A car at rest has constant acceleration. The car travels 10 m in the first 2 seconds. What is the displacement from t = 0s to t = 4s? MUST USE TWO STEPS**** Step 1:- Δx = Vot + (1/2)at2- Δx = (1/2) at2- 10 = (1/2)a(2)2These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- A = 5 m/s2 Step 2:- Δx = (1/2)at2- Δx = (1/2)(5)(4)2- Δx = 40 m- Kinematic Equationso For velocity, accerlation and displacement V = Vo + at Δx = Vot + (1/2)at2 V2 = Vo2 + 2a Δxo Example A race car at rest accelerates at a constant rate of 10 m/s2 A. what is its velocity- Known: acceleration, displacement- Unknown: velocityo 2a Δx = v2 Vo = 0o V = (2000)1/2 = 44.7 m/s How much time is elapsed after it traveled 100m?- V = Vo + at Vo = 0- T = v/a = 44.7/ 10 = 4.47s- 2.6 Free Falling Objectso Neglect air resistanceo Free falling object has constant acceleration near Earth’s surface G = 9.8 m/s2o If it has an initial velocity, it has free fall No other forces acting on ito G always points downwardo **Use y in the positive direction so g is always
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