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Displacement with constant acceleration

Displacement with constant acceleration. How far, how fast?. Review of v avg. We have seen a way to calculate v avg already: v avg = Δ x / t Let’s look at the Old School way to find an average…. Finding an average…. If you wanted to find the average of these numbers: 5,3,7 and 5

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Displacement with constant acceleration

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  1. Displacement with constant acceleration How far, how fast?

  2. Review of vavg • We have seen a way to calculate vavg already: vavg= Δx / t • Let’s look at the Old School way to find an average….

  3. Finding an average… • If you wanted to find the average of these numbers: 5,3,7 and 5 You would just add them up and divide by 4 Mmmk.

  4. Finding an average… • You can do the same thing with velocities • Suppose a car accelerates from 0m/s for 30 sec at 1m/s2. That’s gonna take forever to do!

  5. Finding an average…. • OR… There’s a much easier way: • If acceleration is constant (it always will be for us.) average the first and last velocities and you get the same answer. Oh, good!

  6. Two equations • We now have two ways to find vavg : • Now let’s put them together… Uhhhh…

  7. One equation • 1st: …

  8. One equation • 1st: • Now, substitute in • 2nd: …

  9. One equation • 1st: • Now, substitute in • 2nd: • New Equation: Ok, got it!

  10. Example • A racing car reaches a speed of 42 m/s. It then begins a uniform negative acceleration, using its parachute and braking system, and comes to rest 5.5s later. Find the distance that the car travels during braking.

  11. Example • A racing car reaches a speed of 42 m/s. It then begins a uniform negative acceleration, using its parachute and braking system, and comes to rest 5.5s later. Find the distance that the car travels during braking. • Givens: vi=42 m/s t= 5.5 s vf=0 m/s Δx= ?

  12. Example • A racing car reaches a speed of 42 m/s. It then begins a uniform negative acceleration, using its parachute and braking system, and comes to rest 5.5s later. Find the distance that the car travels during braking. • Givens: vi=42 m/s t= 5.5 s vf=0 m/s Δx= ? • Formula:

  13. Example • A racing car reaches a speed of 42 m/s. It then begins a uniform negative acceleration, using its parachute and braking system, and comes to rest 5.5s later. Find the distance that the car travels during braking. • Givens: vi=42 m/s t= 5.5 s vf=0 m/s Δx= ? • Formula:

  14. Practice • For classwork, complete Practice C, Pg. 53

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