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Chapter 2 Section 2. Acceleration. Acceleration, Speed, & Velocity. Remeber…Speed= Rate of change of position Acceleration is the rate of change of Velocity Acceleration occurs with a change in speed… direction… or both
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Chapter 2 Section 2 Acceleration
Acceleration, Speed, & Velocity • Remeber…Speed= Rate of change of position • Acceleration is the rate of change of Velocity • Acceleration occurs with a change in speed… direction… or both • So if you are going 60 mph and go around a curve while staying at 60… you still have accelerated.
Acceleration (cont.)Changes in Speed • Acceleration is not just speeding up. • Speeding up is POSITIVE accel. • Slowing down is NEGATIVE accel. • Accel can be ANY change in speed.
Acceleration (cont.)Changing directions • Any time an object changes direction, it’s velocity has changed and it is accelerating. • Horses on a carousel are always accel. Because they are constantly changing direction.
Calculating Acceleration • Accceleration= Change in velocity/time • Change in velosity= final velocity – initial velocity • Soooooo • A = (vf – vi) / t • Initial velocity is what you started at… final velocity is what you ended at. • You will end up with an answer that looks like this….
Calculating Acceleration (cont.) • 9.8 m/s/s…. Or… • 9.8 m/s^2 • And is spoken “9.8 meters per second squared”
Calculating Accelerationpositive accel. • A jet is standing still. It starts to take off. It starts at 0 meters per second. And 20 seconds later it reaches 80 m/s. • A=(vf-vi)/t • A= (80 m/s – 0 m/s)/ 20 sec • A= 4 m/s^2
Calculating AccelerationNegative Accel. • A car is traveling 3 m/s and slows down to a stop in 2 seconds. (negative acceleration) • A= (vf-vi)/t • A= (0 m/s – 3m/s)/2 seconds • A = -1.5 m/s^2