1. Student Objective Click below for today’s topic & warmup http://ifaketext.com/img/u4nfr6dt.jpg

2. 2 Student Objective (VSC)  Observe, describe, and compare the motion of objects using velocity.  Describe and calculate acceleration using change in the speed over time. WARM-UP Which animal is the has the fastest speed? A. 10 miles in 2 hours B. 50 miles in 25 hours C. 15 miles in 5 hours

3. Discovery Education: Go to “Assignments” tab Need For Speed Complete worksheet 3

4. Bubble Gum Physics Part A: Chomper Challenge 5 trials 30 seconds each trial Average speed = Add all 5 speeds ÷ 5 Hint: Your average speed x ________ seconds 5 min. = 300 seconds 1 hr. = 3,600 second 1 day = 86,400 seconds Part B: Speedy Chompers Record total number of chomps at 20 sec., 40 sec., & 60 sec. time marks Answer questions on back of worksheet Online Stopwatch

5. 5 Calculating Acceleration As a roller-coaster car starts down a slope, its speed is 4 m/s. But 3 seconds later, at the bottom, its speed is 22 m/s. What is its average acceleration? Read and Understand What information have you been given? Initial speed = 4 m/s Final Speed = 22 m/s Time = 3 s

6. 6 Calculating Acceleration As a roller-coaster car starts down a slope, its speed is 4 m/s. But 3 seconds later, at the bottom, its speed is 22 m/s. What is its average acceleration? Plan and Solve What quantity are you trying to calculate? The average acceleration of the roller-coaster car = __ What formula contains the given quantities and the unknown quantity? Acceleration = (Final speed – Initial speed) ÷ Time Perform the calculation. Acceleration = (22 m/s – 4 m/s)/3 s = m/s/3 s Acceleration = m/s 2 The roller-coaster car’s average acceleration is m/s 2. 18 6 6

7. 7 Calculating Acceleration As a roller-coaster car starts down a slope, its speed is 4 m/s. But 3 seconds later, at the bottom, its speed is 22 m/s. What is its average acceleration? Look Back and Check Does your answer make sense? The answer is reasonable. If the car’s speed increases by 6 m/s each second, its speed will be 10 m/s after 1 second, 16 m/s after 2 seconds, and 22 m/s after 3 seconds.

8. 8 - Acceleration To determine the acceleration of an object moving in a straight line, you must calculate the change in speed per unit of time. Acceleration = (24m/s -0m/s) ÷ 3 m/s = 8 m/s 2

9. 9 Calculating Acceleration A falling raindrop accelerates from 10 m/s to 30 m/s in 2 seconds. What is the raindrop’s average acceleration? A certain car can accelerate from rest to 2.7 m/s in 9 seconds. Find the car’s average acceleration.

10. 10 Calculating Acceleration Practice Problem A falling raindrop accelerates from 10 m/s to 30 m/s in 2 seconds. What is the raindrop’s average acceleration? (30 m/s – 10 m/s) ÷ 2 seconds = 10 m/s 2

11. 11 Calculating Acceleration A certain car can accelerate from rest to 2.7 m/s in 9 seconds. Find the car’s average acceleration. (2.7 m/s – 0 m/s) ÷ 9 s = 2.7 m/s ÷ 9 s = 0.3 m/s 2

12. 12 Conclusion Answer the following questions: If you know an object’s speed and the time they have traveled then you can calculate the _____________. If you know an objects speed and the direction it is travelling in then you know the object’s ____________. Three ways an object can accelerate are _______, _______ and _______. 12

13. Time (in seconds) Distance from last time mark (in meters) Distance from “Start” point (in meters) Speed (distance ÷ 3 sec.) 3 6 9 12 15 18 21 a a