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Acceleration Define acceleration How about scientifically? –Rate of change of velocity What is a rate? What is velocity?

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Presentation on theme: "Acceleration Define acceleration How about scientifically? –Rate of change of velocity What is a rate? What is velocity?"— Presentation transcript:

1 Acceleration Define acceleration How about scientifically? –Rate of change of velocity What is a rate? What is velocity?

2 Acceleration of Selected Events (Smallest to Largest) a (m/s 2 )event 5 × 10 −14 smallest acceleration in a scientific experiment 2 × 10 −10 galactic acceleration at the sun 0.5elevator, hydraulic 1elevator, cable 1.6free fall acceleration on the moon 8.8International Space Station 3.7free fall acceleration on Mars 9.8free fall acceleration on Earth 10–40manned rocket at launch 20space shuttle, peak 24.8free fall acceleration on Jupiter 20–50roller coaster 80limit of sustained human tolerance 0–150human training centrifuge 100–200ejection seat 270free fall acceleration on the sun 600airbags automatically deploy 10 4 –10 6 medical centrifuge 10 6 bullet in the barrel of a gun

3 Automotive Acceleration (g) eventtypical carsports carF-1 race carlarge truck starting0.3–0.50.5–0.91.7< 0.2 braking0.8–1.01.0–1.32~ 0.6 cornering0.7–0.90.9–1.03??

4 Acceleration and the Human Body a (g)event 2.9sneeze 3.5cough 3.6crowd jostle 4.1slap on back 8.1hop off step 10.1plop down in chair 60chest acceleration during car crash at 48 km/h with airbag, design limit 70–100crash that killed Diana, Princess of Wales, –200head acceleration limit during bicycle crash with helmet

5 Types of Acceleration What are three ways that an object can accelerate? What does velocity look like during these times? bug-motion-2dhttp://phet.colorado.edu/en/simulation/lady bug-motion-2d

6 What happened from min? min? min? min? min? min? min? min? min?

7 Acceleration… How do we calculate it? –Think of the definition It is a rate of change of a velocity OR What should the standard SI units look like? –What are the units for velocity? –What are the units of time?

8 Example A cart goes from rest to 10 m/s away from you in 2 s. What is the cart’s acceleration? A skateboarder has an initial velocity of 3 m/s west and comes to a stop in 2 s. What is the skateboarder’s acceleration?

9 Solution A cart goes from rest to 10 m/s away from you in 2 s. What is the cart’s acceleration? a=? v i = 0 m/s v f =10 m/s away t= 2 s

10 Solution A skateboarder has an initial velocity of 3 m/s west and comes to a stop in 2 s. What is the skateboarder’s acceleration? a=? v i = 3 m/s west v f =0 m/s t= 2 s

11 Your turn A car goes from rest to a velocity of 108 km/h north in 10 s. What is the car’s acceleration in m/s? A baseball is pitched at 40 m/s (90 mph) in a Major League game. The batter hits the ball on a line drive straight toward the pitcher at 50 m/s (112 mph). Determine the acceleration of the ball if it was in contact with the bat for 1/30 s.

12 Solution A car goes from rest to a velocity of 108 km/h north in 10 s. What is the car’s acceleration in m/s? a=? v i = 0 m/s v f =108 km/h north= 30m/sNt= 10 s First we need to convert km/h to m/s…

13 Solution A baseball is pitched at 40 m/s (90 mph) in a Major League game. The batter hits the ball on a line drive straight toward the pitcher at 50 m/s (112 mph). Determine the acceleration of the ball if it was in contact with the bat for 1/30 s. a=? t= 1/30 s v f =50 m/s towards the pitcher orv i = 40 m/s towards the batter or v f =-50 m/s towards the batter v i = -40 m/s towards the pitcher Our issue is that we can’t calculate the acceleration unless the velocities are in like terms. We can flip either velocity, when we do this we must change the sign (positive to negative or vice versa). Once we do that we can solve as usual!

14 Two Dimension Motion Circular motion –We looked at this before motion-2dhttp://phet.colorado.edu/en/simulation/ladybug- motion-2d Centripetal acceleration –What do you think this is? Hint: Think about the acceleration of the lady bug.

15 Projectile Motion What is a projectile? What path does a projectile travel? What are the two components of projectile motion? V h = 2.0 m/s V v = 0.0 m/s V v = 0.5 m/s V v = 1.0 m/s

16 Throwing vs. Dropping Will a ball that is thrown as hard as you can throw it and an identical ball dropped (zero added force) straight down land at the same time or different times? Why? Video

17 Amusement Parks mh6Z8http://www.youtube.com/watch?v=0WpNSI mh6Z8 How do amusement park rides create “thrills”? What do you feel when you are on roller coasters or waterslides?


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