Finding Slope Review Find the slope of this

Finding Slope Review • Find the slope of this line • Remember (y 2 -y 1)/(x 2 -x 1) • What speed is this object going?

Finding Slope Review (2) • Find the speed the car was travelling at for the first 10 seconds • Find the speed the car was travelling at from 10 -20 seconds • Find the speed the car was travelling at from 20 -30 seconds

Where is the speed fastest? Zero?

Chapter 4, Section 3 Acceleration http: //science. howstuffworks. com/transport/acceleration-videos-playlist. htm Video 5 - Athletic Cheetahs

Acceleration • acceleration: the rate at which your speed (or velocity) changes

Acceleration • acceleration = the slope of a speed-time graph What is the acceleration of the bike?

Acceleration steeper line = greater acceleration

Acceleration and Speed • Speed and acceleration are not the same • If you are moving at a constant speed, you have no acceleration http: //study. com/academy/lesson/what-is-acceleration-definition-and-formula. html

Acceleration and Speed • Acceleration describes any change in speed • + a = increasing speed • - a = decreasing speed

Units of Acceleration • (V 2 -V 1) / t • (m/s – m/s) /s • (m/s) / s = m/s/s = m/s 2 m 2 s

Example Problem 1 • A car begins going 20 m/s, and speeds up to 30 m/s in 5 seconds. What is the car’s acceleration? • (V 2 -V 1) / t • (30 m/s – 20 m/s) / 5 s = 10/5 = 2 m/s 2

Example Problem 2 • An airplane takes off starting at a speed of 10 m/s and changing to a speed of 510 m/s. It took the plane 20 seconds to reach this final speed, what is the acceleration? • (510 m/s - 10 m/s) / 20 s = 25 m/s 2

Example Problem 3 • A train accelerates at 5 m/s 2 to get from 40 m/s to 100 m/s. How much time does it take the train to get to this final speed? • • (100 -40)/t = 5 (100 -40) = 5 t (100 -40)/5 = t 60/5 = t = 12 seconds

Example Problem 4 • A boat accelerates at 2 m/s 2 to get from 10 m/s to 50 m/s. How much time does it take the train to get to this final speed? • • (50 -10)/t = 2 (50 -10) = 2 t (40)/2 = t 20 = t = 20 seconds

Example Problem 5 • A snowboarder travelling down a slope accelerates at 2 m/s 2. If the snowboarder started at 0 m/s, what is her final velocity after 10 seconds? • (V 2 – V 1)/t = a • (V 2 – 0)/10 = 2 • (V 2 – 0) = 20 V 2 = 20 m/s

Example Problem 6 • A helicopter starting at 10 m/s accelerates at a rate of 8 m/s 2. What is the final speed after 4. 0 seconds? • (V 2 – 10)/4. 0 = 8 • (V 2 – 10) = 32. • V 2 = 32 + 10 = 42 m/s

Acceleration and Graphs of Motion • The position-time graph is curved when an object accelerates

Acceleration & Speed vs. Time

Acceleration & Speed vs. Time 1. Determine the slope of the line between 0 s and 4 s. What does the slope of the line tell you about the acceleration of the car during this time interval? 2. Describe the speed of the car between 5 and 7 s. What does this tell you about the car’s acceleration? 3. What is the slope of the line between 7 and 9 s? What does this tell you about the car’s acceleration?