Notes 4 3 Acceleration Acceleration rate of change

• Acceleration – rate of change in velocity. • Remember: velocity includes speed

Equation: Acceleration = (Final Velocity – Initial Velocity) Time = ∆v t Units:

• Example: A roller coaster increases its velocity from 23 m/s to 62

• Example: The Steel Venom is accelerated at a rate of 15 m/s

• Example: Driving to school, you see a deer in the road. You

When am I not accelerating? 1 - When I am AT REST (not moving)

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Notes 4. 3: Acceleration

• Acceleration – rate of change in velocity. • Remember: velocity includes speed and direction so acceleration could be: • 1 - a change in speed • 2 - or direction • 3 - or both. • Acceleration is a VECTOR (has speed and direction)

Equation: Acceleration = (Final Velocity – Initial Velocity) Time = ∆v t Units:

• Example: A roller coaster increases its velocity from 23 m/s to 62 m/s in 4. 2 seconds. At what rate did the roller coaster accelerate? Answer: V 1 = 23 m/s V 2 = 62 m/s t = 4. 2 s a=? a = 9. 3 m/s 2

• Example: The Steel Venom is accelerated at a rate of 15 m/s 2. If it starts at rest, how long will it take to reach a speed of 50 m/s? • Answer: V 1 = 0 m/s V 2 = 50 m/s t=? a = 15 m/s 2 t = 3. 3 sec

• Example: Driving to school, you see a deer in the road. You slam on your brakes and your velocity goes from 20 m/s to 5 m/s in 1. 5 sec. What was your acceleration? V 1 = 20 m/s V 2 = 5 m/s t = 1. 5 sec a=? a = -10 m/s 2 The negative value means slowing down.

When am I not accelerating? 1 - When I am AT REST (not moving) 2 - When I am MOVING AT A CONSTANT VELOCITY (cruise control in a car) * Note: I said constant VELOCITY, . . NOT constant SPEED How could I be moving at a constant SPEED and still accelerating? By changing my direction !