What is Velocity? Velocity refers to speed in a particular directionVelocity refers to speed in a particular direction To accurately describe an object’s motion, it is necessary to give its speed and directionTo accurately describe an object’s motion, it is necessary to give its speed and direction Ex: You ride your bike 20 km/hr eastEx: You ride your bike 20 km/hr east Ex: I drive my car 95 km/hr southwest when I go home.Ex: I drive my car 95 km/hr southwest when I go home. If two velocities are headed in the same direction, they can be added together.If two velocities are headed in the same direction, they can be added together. Ex: A train is headed 60 M/hr East. A passenger on the train is walking 3 M/hr east. The passenger’s total motion is 63 M/hr headed East.Ex: A train is headed 60 M/hr East. A passenger on the train is walking 3 M/hr east. The passenger’s total motion is 63 M/hr headed East. If two velocities are headed in opposite directions, they can be subtracted.If two velocities are headed in opposite directions, they can be subtracted. Ex: A train is headed 60 M/hr East. A passenger on the train is walking 3 M/hr West. The passenger’s total motion is 57 M/hr headed West.Ex: A train is headed 60 M/hr East. A passenger on the train is walking 3 M/hr West. The passenger’s total motion is 57 M/hr headed West.

Acceleration Acceleration is a change in speed or directionAcceleration is a change in speed or direction It is simply a change in velocityIt is simply a change in velocity Calculate the speed after 3 seconds:Calculate the speed after 3 seconds: Calculate the speed at 6 seconds:Calculate the speed at 6 seconds: Calculate speed at 9 seconds:Calculate speed at 9 seconds: Notice the object’s speed is increasing over timeNotice the object’s speed is increasing over time 50 ÷ 3 = 16.6 m/sec 200 ÷ 6 = 33.3 m/sec 400 ÷ 9 = 44.4 m/sec

Analyzing Graphs Positive Acceleration Negative Acceleration / Deceleration Positive acceleration is when an object’s speed is increasing over timePositive acceleration is when an object’s speed is increasing over time A graph with an upward slope is shownA graph with an upward slope is shown Negative acceleration (deceleration) is when an object’s speed is decreasing over timeNegative acceleration (deceleration) is when an object’s speed is decreasing over time A graph with a downward slope is shownA graph with a downward slope is shown At Point A, Speed = 83.3 m/sec At Point B, Speed = 30 m/sec At point C, Speed = 7.1 m/sec

How to calculate Acceleration Acceleration = Final Velocity – Original velocity TimeAcceleration = Final Velocity – Original velocity Time A = Vf – VoA = Vf – Vo Time Time If acceleration is increasing, it is referred to as positive acceleration, and your answer will be a positive numberIf acceleration is increasing, it is referred to as positive acceleration, and your answer will be a positive number If acceleration is decreasing (becoming negative), it is called deceleration or negative acceleration, and your answer will be a negative number.If acceleration is decreasing (becoming negative), it is called deceleration or negative acceleration, and your answer will be a negative number.

Calculating Acceleration: A rollercoaster is traveling 15 meters/second at the top of a hill. After 3 seconds, it is traveling 30 meters/second when it reaches the lower part of the hill. What is the rollercoaster's acceleration?A rollercoaster is traveling 15 meters/second at the top of a hill. After 3 seconds, it is traveling 30 meters/second when it reaches the lower part of the hill. What is the rollercoaster's acceleration? A = Vf – Vo Time 30 m/s – 15 m/s = 15 m/s 3 sec 3 sec A = 5 m/s/s or 5 m/s 2

Calculating Deceleration: If a car's velocity changes from 50 meters/second to 20 meters / second in 5 seconds, what was the object's acceleration?If a car's velocity changes from 50 meters/second to 20 meters / second in 5 seconds, what was the object's acceleration? A = Vf – Vo Time 20 m/s – 50 m/s = -30 m/s 5 sec 5 sec A = -6 m/s/s or -6 m/s 2