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Physics. For scalar quantities just look at the magnitude Ex: Speed For vector quantities you have to consider direction and magnitude Ex: Velocity and.

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Presentation on theme: "Physics. For scalar quantities just look at the magnitude Ex: Speed For vector quantities you have to consider direction and magnitude Ex: Velocity and."— Presentation transcript:

1 Physics

2 For scalar quantities just look at the magnitude Ex: Speed For vector quantities you have to consider direction and magnitude Ex: Velocity and Acceleration

3 Speed is… Total distance traveled/ Δt YumaEckle y Wray 14 miles in 10 minutes 27 miles in 23 minutes

4 Speed is… Total distance traveled = = 41 miles Total Time = 33 minutes = 0.55 hours Speed = 41 miles / 0.55 hrs = 75 mi/hr YumaEckle y Wray 14 miles in 10 minutes 27 miles in 23 minutes

5 Velocity is… the change in distance (Δd) / Δt YumaEckle y Wray 14 miles in 10 minutes 27 miles in 23 minutes

6 Velocity is Δd = 13 miles East Δt = 41 minutes = 0.55 hrs V = 13/ 0.55 = 24 mi / hr EAST YumaEckle y Wray 14 miles in 10 minutes 27 miles in 23 minutes

7 Calculate the speed and velocity of the following… A trackster who runs 2 complete laps on a track (0.5 mi) in 3 minutes (0.05 hrs) Speed = Velocity = 0.5/0.05 = 10 mi/hr 0.0/0.05 = 0 mi/hr A trackster who runs 2.5 complete laps on a track (0.625 mi) in 3.5 minutes ( hrs) Speed = Velocity = 0.625/ = mi/hr 0.125/ = 2.14 mi/hr

8 Acceleration is a change in velocity over a change in time It is a VECTOR quantity Acceleration in the direction of movement speeds up an object Acceleration that is in the opposite direction of movement slows down an object Deceleration

9 Negative Acceleration that opposes the direction of movement…deceleration Positive Acceleration in the direction of movement Negative Acceleration and then Positive Acceleration

10 Velocity vs. Time Graphs Average Acceleration =ΔV/Δt -Units = m/s 2 Instant Acceleration -tangent line to a specific point -In this example Average Acceleration = Instantaneous Acceleration -Units = m/s 2

11 What is the Instantaneous Acceleration at… 1.5 seconds 6.5 seconds 2.5 seconds Slope = 0 = acceleration Slope = (2 m/s)/ 1 s = 2 m/s 2 = acceleration Slope = (-2 m/s)/ 1 s = -2 m/s 2 = acceleration

12 1-2 seconds 2-7 seconds 1-3 seconds = (1-1 m/s) / 1 s = 0 m/s 2 = (3-1 m/s) / 2 s = 1 m/s 2 = (2-1 m/s) / 5 s = 0.2 m/s 2 What is the Average Acceleration from…

13 0-6 seconds 1 second 8-10 seconds = (30-10 m/s) / 6 s = 3.3 m/s 2 = (10-60 m/s) / 2 s = -25 m/s 2 What is the Average Acceleration from… What is the Instantaneous Acceleration at… 8.5 seconds Slope = (40 m/s)/ 2 s = 20 m/s 2 = acceleration Slope = (-40 m/s)/ 1 s = - 40 m/s 2 = acceleration

14 A car travels for 10 seconds. What is the final velocity of a car with an initial velocity of 10 m/s and an acceleration of 20 m/s 2. Acceleration = ΔV/Δt = (V final – V initial )/ (t final – t initial ) V final = ??? V initial = 10 m/s Δt = 10 s Acceleration = 20 m/s 2 20 m/s 2 = (V final – 10 m/s)/ (10 seconds) 10 seconds*20 m/s 2 = (V final – 10 m/s) 200 m/s = (V final – 10 m/s) 200 m/s + 10 m/s = (V final ) 210 m/s = V final

15 Velocity vs TimeAcceleration vs Time

16 Chapter 3 Problems 54, 59, 60, 80, 82, 86a


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