1. Physics – Chapter 2, Section 2 St. Augustine Preparatory School August 24, 2015

2. Previously… V ave = (x f -x i )/(t f -t i ) a ave = (v f -v i )/(t f -t i ) We are going to add a few more formulas to our list today

3. Displacement with Constant Acceleration We can use this formula to find displacement if the acceleration is constant, but not known: Example question: When Maggie applies the brakes of her car, the car slows uniformly from 15.0m/s to 0.00m/s in 2.50s. How many meters before a stop sign must she apply her brakes to stop in time?

4. Finding final velocity with constant acceleration We can use this formula to find final velocity if the acceleration is constant and known: v f = v i + aΔt Example: An automobile with an initial speed of 4.30m/s accelerates uniformly at the rate of 3.00m/s 2. Find the final speed after 5.0s.

5. Displacement with Constant Acceleration We can use this formula to find displacement if the acceleration is constant, but known: Note: the time is squared at the end

6. Final velocity after any displacement If the initial velocity, acceleration and displacement are known, we can calculate the final velocity without knowing the time: Remember when solving for square roots, you will get both a positive and negative answer. You have to decide which to keep

7. Example A person pushing a stroller starts from rest, uniformly accelerating at a rate of 0.500 m/s 2. What is the velocity of the stroller after it has travelled 4.75m.

8. Practice Problems Page 49: 1, 4 Page 51: 3, 4 Page 54: 1-6