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Notes 9-3. Acceleration. Acceleration. Rate velocity changes with time Vector quantity In science, acceleration refers to increasing speed, decreasing speed, or changing direction Decreasing speed = deceleration. Chapter 9 Motion and Energy. Calculating Acceleration.
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Notes 9-3 Acceleration
Acceleration • Rate velocity changes with time • Vector quantity • In science, acceleration refers to increasing speed, decreasing speed, or changing direction • Decreasing speed = deceleration
Chapter 9 Motion and Energy Calculating Acceleration • To determine the acceleration of an object, you must calculate its change in velocity per unit of time. • Acceleration = Final Velocity – Initial Velocity Time
Let’s Try a Problem • Calculate the plane’s acceleration in the first 5 seconds of motion. A= Vf – Vi time A = 40 m/s – 0 m/s 5 s A = 8 m/s2
As a roller-coaster car starts down a slope, its velocity is 4 m/s. But 3 seconds later, its velocity is 22 m/s in the same direction. What is its acceleration? Read and Understand What information have you been given? Initial velocity = 4 m/s Final velocity = 22 m/s Time = 3 s Chapter 9 Motion and Energy Calculating Acceleration
As a roller-coaster car starts down a slope, its velocity is 4 m/s. But 3 seconds later, its velocity is 22 m/s in the same direction. What is its acceleration? Plan and Solve What quantity are you trying to calculate? The acceleration of the roller-coaster car = __ What formula contains the given quantities and the unknown quantity? Acceleration = (Final velocity - Initial velocity)/Time Perform the calculation. Acceleration = (22 m/s - 4 m/s)/3 s = 18 m/s/3s Acceleration = 6 m/s2 The acceleration is 6 m/s2 down the slope . Chapter 9 Motion and Energy Calculating Acceleration
As a roller-coaster car starts down a slope, its velocity is 4 m/s. But 3 seconds later, its velocity is 22 m/s in the same direction. What is its acceleration? Look Back and Check Does your answer make sense? The answer is reasonable. If the car’s velocity increases by 6 m/s each second, its velocity will be 10 m/s after 1 second, 16 m/s after 2 seconds, and 22 m/s after 3 seconds. Chapter 9 Motion and Energy Calculating Acceleration
Practice Problem A falling raindrop accelerates from 10 m/s to 30 m/s in 2 seconds. What is the raindrop’s acceleration? (30 m/s - 10 m/s) ÷ 2 seconds = 10 m/s2 Chapter 9 Motion and Energy Calculating Acceleration
Practice Problem A certain car can accelerate from rest to 27 m/s in 9 seconds. Find the car’s acceleration. (27 m/s - 0 m/s) ÷ 9 s = 27 m/s ÷ 9 s = 3 m/s2 Chapter 9 Motion and Energy Calculating Acceleration
Chapter 9 Motion and Energy Graphing Acceleration • You can use both a speed-versus-time graph and a distance-versus-time graph to analyze the motion of an accelerating object.
Mr. Edmonds!! • http://youtu.be/4CWlNoNpXCc