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think! Suppose a car moving in a straight line steadily increases its speed each second, first from 35 to 40 km/h, then from 40 to 45 km/h, then from 45 to 50 km/h. What is its acceleration?. 5 km/h 5 km/s - 5 km/ h•s 5 km/ h•s 35 km/h 40 km/ h•s 45 km/h 50 km/ h•s.
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think!Suppose a car moving in a straight line steadily increases its speed each second, first from 35 to 40 km/h, then from 40 to 45 km/h, then from 45 to 50 km/h. What is its acceleration? • 5 km/h • 5 km/s • -5 km/h•s • 5 km/h•s • 35 km/h • 40 km/h•s • 45 km/h • 50 km/h•s
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What should I be thinking as I answer this question… • Acceleration has TWO units of time, which rules out some of my answers: • 5 km/h • 5 km/s • -5 km/h•s • 5 km/h•s • 35 km/h • 40 km/h•s • 45 km/h • 50 km/h•s
What should I be thinking as I answer this question… • Acceleration is the CHANGE in velocity divided by time… which means it is the FINAL VELOCITY – INITIAL VELOCITY. In this case, I know the car is SPEEDING UP, which is a POSITIVE acceleration: -5 km/h•s 5 km/h•s 40 km/h•s 50 km/h•s
What should I be thinking as I answer this question… • Acceleration is the CHANGE in velocity divided by time… which means: • It is the FINAL VELOCITY – INITIAL VELOCITY, divided by the change in time. In this case, the car is CHANGING its velocity by 5 km/h every 1 s… so, 5 km/h divided by 1s = -5 km/h•s 5 km/h•s 40 km/h•s 50 km/h•s
think!In 5 seconds a car moving in a straight line increases its speed from 50 km/h to 65 km/h, while a truck goes from rest to 15 km/h in a straight line. Which undergoes greater acceleration? What is the acceleration of each vehicle? • The car undergoes the greater acceleration because it is moving faster than the truck (5065 km/h) • The truck undergoes the greater acceleration because it is more massive than the car • They both undergo the same acceleration because they both change their velocity by the same amount (inc. of 15 km/h) in the same time interval (5 s )
Don’t forget: You can copy-paste this slide into other presentations, and move or resize the poll.
What should I be thinking as I answer this question… • Acceleration is the CHANGE in VELOCITY, divided by time… • Both vehicles CHANGE their velocity by 15 km/h • More specifically…Both vehicles INCREASE their velocity by 15 km/h • Both vehicles make this CHANGE in the same amount of time… • Both vehicles have the same acceleration! • **Acceleration is NOT how fast you move; it is how quicklyyou can CHANGE how fast you move.
Peer Review HW • You have 5 minutes to meet with peers and discuss HW. • Questions? Ask a teacher! • Done? Get started on Concept Development! (See teacher for a copy)
Concept Attainment… • As a class, we are going to complete #1 on page 3 See the board • Right Now: finish concept attainment; check in at stop signs (will have a few minutes next class to finish checking in) • EXIT SLIP – 5 minutes before end of class; turn in when done