Preliminary Questions 2B.1.1: Position, Velocity, Acceleration Plots The plot to the right...
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Transcript of Preliminary Questions 2B.1.1: Position, Velocity, Acceleration Plots The plot to the right...
Preliminary Questions 2B.1.1: Position, Velocity, Acceleration Plots
The plot to the right represents the motion of an object.
• During period 1, the object’s velocity is increasing, constant, or decreasing?
• Determine the velocity of the object at 20.0 s.
• During period 1, the object’s acceleration is positive, zero, or negative? Increasing, constant, or decreasing?
• Determine the acceleration of the object between 0.0 s and 15.0 s.
• Determine the distance traveled by the object during the first 10.0 s.
Prelim Q KEY 2B.1.1: Position, Velocity, Acceleration Plots
1. During period 1, the object’s velocity is increasing, constant, or decreasing?
First, note that the plot is of velocity [vertical] vs. time [horizontal]
Velocity starts the period at 0 m/s and increases uniformly to 15.0 m/s.
2. Determine the velocity of the object at 20.0 s.
15.0 m/s.
- Go to 20.0 s on the horizontal axis.- Move straight up [vertically] until you reach the plot [green, point B].- Move straight left [horizontally] until you reach the vertical axis [velocity].- Read the value.
Prelim Q KEY 2B.1.1: Position, Velocity, Acceleration Plots
3. During period 1, the object’s acceleration
is positive, zero, or negative?
Increasing, constant, or decreasing?
Acceleration = slope of v vs. t plot.
Slope between 0.0 s and 15.0 s is positive and does not change.
4. Determine the acceleration of the object between 0.0 s and 15.0 s.
ss
m
ss
m
sss
ms
m
tt
vv
t
va
initialfinal
initialfinal
00.10.15
0.15
0.00.15
0.00.15
Prelim Q KEY 2B.1.1: Position, Velocity, Acceleration Plots
5. Determine the distance traveled by the object during the first 10.0 s.
Distance from a v vs. t plot:Area under the curve.
Area of a triangle = ½ (base) (height)= ½ (10.0s) (10.0 m/s) = 50 m
OR:Distance = (avg. velocity) (time interval)
mssmss
m
sssm
sm
tvd avg
501050.102
0.10
0.00.102
0.100.0
Follow up questions. 2B.1.1: Position, Velocity, Acceleration Plots
The plot to the right represents the motion of an object.
• During period 2, the object’s velocity is positive, zero, or negative? Increasing, constant, or decreasing?
• During period 2, the object’s acceleration is positive, zero, or negative? Increasing, constant, or decreasing?
• Determine the acceleration of the object during period 2.
• Determine the distance traveled by the object during period 2.
• Determine the velocity of the object at 10.0 s.
KEY. Follow up. 2B.1.1: Position, Velocity, Acceleration Plots
The plot to the right represents the motion of an object.
• During period 2, the object’s velocity is positive, zero, or negative? Increasing, constant, or decreasing?
• During period 2, the object’s acceleration is positive, zero, or negative? Increasing, constant, or decreasing?
• Determine the acceleration of the object during period 2. Slope = zero.
• Determine the distance traveled by the object during period 2. (15 m/s)(5 s)=75 m
• Determine the velocity of the object at 10.0 s. 10.0 m/s.
Follow up questions, 2. 2B.1.1: Position, Velocity, Acceleration Plots
The plot to the right represents the motion of an object.
• During period 3, the object’s velocity is positive, zero, or negative? Increasing, constant, or decreasing?
• Determine the velocity of the object at 25.0 s.
• During period 3, the object’s acceleration is positive, zero, or negative? Increasing, constant, or decreasing?
• Determine the acceleration of the object during period 3.
• Determine the distance traveled by the object during period 3.
KEY. Follow up 2. 2B.1.1: Position, Velocity, Acceleration Plots
The plot to the right represents the motion of an object.
• During period 3, the object’s velocity is positive, zero, or negative? Increasing, constant, or decreasing?
• Determine the velocity of the object at 25.0 s. 5.0 m/s.
• During period 3, the object’s acceleration is positive, zero, or negative? Increasing, constant, or decreasing? Slope of a line is constant. Slope is negative.
• Determine the acceleration of the object during period 3. (15m/s – 5m/s)/(25s – 20s)=10/5=2m/s/s
• Determine the distance traveled by the object during period 3. ((15m/s + 5m/s) / 2) (25s – 20s) = 50m