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Direction of Acceleration and Velocity. Velocity and Acceleration of the car are depicted by vector arrows.Direction of arrows ? Direction of Velocity and Acceleration vectors. Velocity vector is always directed in same direction which car is moving. Accelerating objects have a changing velocity
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1. Acceleration A vector quantity (direction matters)
Rate at which an object changes its velocity (vector)
3 ways to accelerate:
change in speed (increase or decrease)
change in direction
change in speed AND direction
Deceleration
Slowing down (velocity decreases)
2. Direction of Acceleration and Velocity Velocity and Acceleration of the car are depicted by vector arrows.
Direction of arrows ? Direction of Velocity and Acceleration vectors.
Velocity vector is always directed in same direction which car is moving.
Accelerating objects have a changing velocity
Due to a speed change (speeding up or slowing down)
Due to a direction change (going around a curve)
3. Direction of Acceleration and Velocity Car accelerates:
1) Moving down the incline ? Car gains speed
? Positive Acceleration
2) Along straight sections of track ? Car slows down slightly (due to air resistance forces)
? Negative Acceleration (or Deceleration).
3) Along 180-degree curve ? Car changing its direction
? Acceleration due to change in direction.
4. Constant Acceleration For data shown, velocity increases by
________ m/s from 0-1 sec
________ m/s from 1-2 sec
________ m/s from 2-3 sec
________ m/s from 3-4 sec
Constant acceleration is a change in velocity by _______________ amount each second.
5. Changing Acceleration For data shown, velocity increases by
________ m/s from 0-1 sec
________ m/s from 1-2 sec
________ m/s from 2-3 sec
________ m/s from 3-4 sec
Changing acceleration is a change in velocity by _______________ amount each second.
6. Direction of the Acceleration Vector Acceleration is a vector quantity so it will always have a direction associated with it.
Direction of the acceleration vector depends on two factors:
Whether object is speeding up or slowing down
Whether object is moving in positive (+) or negative () direction
If object is slowing down, its acceleration is in opposite direction of motion.
Acceleration will be negative. SHOULD MOVE TO FREE FALLSHOULD MOVE TO FREE FALL
7. Example A & B Example A ? Object moving in positive direction (i.e., positive velocity)
? Speeding up.
Object speeding up ? Acceleration in same direction as Velocity
? Object has a positive acceleration.
Example B ? Object moving in negative direction (i.e., negative velocity)
? Slowing down.
Object slowing down ? Acceleration in opposite direction as Velocity
? Object also has a positive acceleration. SHOULD MOVE TO FREE FALLSHOULD MOVE TO FREE FALL
8. Example C & D Example C ? Object moving in positive direction (i.e., positive velocity)
? Slowing down.
Object slowing down ? Acceleration in opposite direction as Velocity
? Object has a negative acceleration.
Example D ? Object moving in negative direction (i.e., negative velocity)
?Speeding up.
Object speeding up ? Acceleration in same direction as Velocity
? Object has a negative acceleration. SHOULD MOVE TO FREE FALLSHOULD MOVE TO FREE FALL
9. A car accelerates from rest to 40 m/s in 5 seconds. What is the cars acceleration?
10. A car accelerates at a rate of 6 m/s2 for 7 seconds. If the car was originally at rest, how fast is it moving now?
11. A car is originally at rest. It then accelerates at a rate of 3 m/s2 for 6 seconds until it is traveling at 60 m/s. How long does it have to accelerate until it reaches this speed?
12. A vehicle is moving at a velocity of 20 m/s and decelerates at a rate of 5 m/s2 . How long does it take for it to come to a complete stop?
13. Which car or cars (red, green, and/or blue) are accelerating?
14. What distance is traveled by a train as it is accelerated uniformly from 22 m/s to 44 m/s in a 20 second period?
15. A plane flying at the speed of 150m/s is accelerated uniformly at a rate of 5m/s2. a) What is the planes speed at the end of 10 seconds?
b) What distance has it traveled?