A 10 m B 70 m C 30 m D 10 m E 70 m 18 Describing motion1Motion

# A 10 m b 70 m c 30 m d 10 m e 70 m 18 describing

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A) 1.0 m B) 7.0 m C) 3.0 m D) - 1.0 m E) - 7.0 m 18 Describing motion(1.Motion Diagrams,2.Graphs,3.Equations); Position and displacement; Velocity; Acceleration; Free Fall Constant Average Velocity and Uniform Motion: Uniform motion : Characterized by equal displacements in equal time intervals= Constant velocity . Straight line in position vs. time graph. Slope = rise/run = change in pos./time interval. This is the average velocity. (Unit: m/s) i f i f avg t t x x t x v = Δ Δ = x t 7 19 Which position-versus-time graph represents the motion shown in the motion diagram? (A) (B) (C) (D) (E) Question 20 Describing motion(1.Motion Diagrams,2.Graphs,3.Equations); Position and displacement; Velocity; Acceleration; Free Fall – Curved parts in position vs. time graph – The average velocity in time interval t 2 – t 1 is 1 2 1 2 t t x x t x v avg = Δ Δ = •Non-Uniform Motion characterized by an acceleration or deceleration: 21 Describing motion(1.Motion Diagrams,2.Graphs,3.Equations); Position and displacement; Velocity; Acceleration; Free Fall dt dx t x v t = Δ Δ = Δ 0 lim Can we determine the instantaneous velocity at a single point in time from the graph In a plot of the position vs. time, the instantaneous velocity is the slope (or tangent) at every point of the curve. 8 22 Describing motion(1.Motion Diagrams,2.Graphs,3.Equations); Position and displacement; Velocity; Acceleration ; Free Fall In a plot of the velocity vs. time , the acceleration is the slope at every point of the curve. Average acceleration = change in velocity in time interval Δ t: SI unit: m/s 2 Phys 100: Constant acceleration, so a = a avg . i f i f avg t t v v t v a = Δ Δ = v t t i t f v f v i 23 Question When an object is slowing down (deceleration), what happens? – (Hint: think of a ball tossed up vertically.) A) There is no acceleration. B) There is not enough acceleration. C) Acceleration and velocity are in opposite directions. D) None of the above. 24 Question If you toss a ball up, at the highest point A. The velocity changes direction. B. The acceleration changes direction. C. The acceleration is zero. D. Both velocity and acceleration are zero. E. More than one of the above is correct. 9 25 Problem -25 -20 -15 -10 -5 0 5 10 15 20 25 0 5 10 15 20 Time (min) Velocity (km/h) The graph shows your bike trip to the coffee shop. What is the displacement and the total distance? 26 Solution -25 -20 -15 -10 -5 0 5 10 15 20 25 0 5 10 15 20 Time (min) Velocity (km/h) The graph shows your bike trip to the coffee shop. What is the displacement and the total distance?  #### You've reached the end of your free preview.

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• Spring '09
• Lioudmila
• Acceleration, Velocity, Vavg
• • •  