文档介绍：Displacement vs. Distance
Displacement: Change in position (vector)
Distance: How far an object has travelled (scalar)
Symbol: Δx or Δx
SI Unit: meter, m
1-D Kinematics:
start
stop
Displacement, the shortest distance between any 2 points
Distance is the total distance travelled.
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Speed (v) – how fast you go(scalar).
Velocity (v) – how fast and which way; the rate at which position changes(vector).
Average speed ( v ) – distance / time
Acceleration (a) – how fast you speed up, slow down, or change direction; the rate at which velocity changes(vector).
Speed, Velocity, & Acceleration
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Instantaneous Velocity is given by:
Instantaneous velocity & Average velocity
Position vs. Time Graph
Average velocity is given by
Notice that the difference between average velocity and instantaneous velocity is in instantaneous velocity, the time is limit tends to zero.
∆x = xf-x0 (displacement)
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Instantaneous VS Average Velocity
As ∆t approaches zero, then average velocity becomes instantaneous velocity.
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What are the velocities?
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Instantaneous speed is simply the magnitude of instantaneous velocity.
Instantaneous speed= |v(t)|
Average speed is the ratio of total distance covered by total time takes.
Instantaneous and Average Speed
Remember the difference between average speed and average velocity.
Average speed is the ratio of total distance to total time taken.
Average velocity is the ratio of total displacement to the total time taken.
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Average Velocity and Average Speed
We know that, Total Distance ≥ Displacement
So for same ∆t, Average Speed ≥ Average Velocity
A person runs 10 laps around a circular track in 20 minutes, what is his average velocity and average speed?
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Instantaneous Acceleration
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Average Acceleration is given by:
Average Acceleration
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Instantaneous Acceleration vs Average Acceleration from a v-t graph
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