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(d vs t)  B. Interpreting Motion Diagrams

Acceleration Review

Acceleration - the time rate of change in velocity

a = ∆V/∆t = (Vf - Vi)/t

 Uniform Acceleration?

- constant  change
in velocity per unit time

Which data shows uniform acceleration? Why?

 time (sec) Velocity (m/s) 0 5 1 7 2 9 3 11 4 13
 time (sec) Velocity (m/s) 0 5 1 10 2 14 3 20 4 30

Left Data Shows Constant Acceleration

a = ?

a = 2 m/s2

Non-Constant OR Constant Acceleratio? Ex) Describe the acceleration acceleration is constant +

Constant Non-Constant Acceleration? Prove this is constant acceleration Every 2 seconds the object gains exactly 15 m/s

Motion Map

Velocity

0 m/s / 15 m/s / 30 m/s / 45 m/s 0 sec / 2 sec / 2 sec / 2 sec Find the acceleration

a = ∆V/∆t

(+15 m/s)/2 sec

a = +7.5 m/s2 Motion Map

Acceleration

2 sec / 2 sec / 2 sec / 2 sec +7.5 m/s2/+7.5 m/s2/+7.5 m/s2/+7.5 m/s2

Motion Map

Displacement Slope of a V vs. t plot

Slope = ∆y/∆x

= ∆V/∆t = a

Ex)

Describe motion using
y axis and slope Step 1: y axis:

Step 2: Slope

Step 1: y axis: V constant

Step 2: Slope = ∆V/∆t  = a

a = 0 Ranking Task Rank the acceleration from largest to smallest January 2001 Regents

 Ex 4) Step 1: y axis:     Step 2: Slope   Answers   Velocity is Decreasing,   Acceleration is constant, negative     Calculate the acceleration a = (Vf- Vi)/t      (15 m/s - 45 m/s )     (8 sec - 2 sec)      = -5 m/s2    Ex 5) Describe the motions Velocity (m/s) Step 1: y axis: Step 2: Slope   Answers Step 1: y axis:  V increasing     Step 2: Slope = ∆V/∆t  = a a is increasing   Ex) Describe the motions Step 1: y axis: Step 2: Slope           Step 1: y axis: d increasing Step 2: Slope = d/t = V   Velocity is increasing smoothly  Acceleration is constant & Positive   Non-Uniform Acceleration Ex) Describe motions Step 1: y axis: Step 2: Slope           Step 1: y axis: d increasing Step 2: Slope = d/t = v Velocity is Decreasing smoothly (slope)   Acceleration is constant & negative Describe motions d (cm) Step 1: y axis: Step 2: Slope      Step 1: y axis: d constant Step 2: Slope = d/t = v   v = 0 (slope) a = 0         Analyzing Motion Plots - HTML5 St. Mary's H.S.  Summary  ©Tony Mangiacapre., - All Rights Reserved [Home] Established 1995 Use any material on this site (w/ attribution)