physics 151 week 3 day 2 topics – motion diagrams & motion graphs – motion definitions –...
TRANSCRIPT
Physics 151 Week 3 Day 2
Topics– Motion Diagrams & Motion Graphs– Motion Definitions– Velocity to position– Adding and Subtracting Vectors Graphically
Slide 2-34
Where’s the train?
A train is moving at a steady 30 m/s. At t = 0, the engine passes a signal light at x = 0. Without using any formulas, find the engine's position at t = 1s, 2s, and 3s.
Express your reasoning in words.
Slide 2-34
Where’s the train?
A train is moving at a steady 30 m/s. At t = 0, the engine passes a signal light at x = 0. Without using any formulas, find the engine's position at t = 1s, 2s, and 3s.
Express your reasoning in words.
Checking Understanding 1Two runners jog along a track. The positions are shown at 1 s time intervals. Which runner is moving faster?
Slide 1-21
Two runners jog along a track. The positions are shown at 1 s time intervals. Which runner is moving faster?
Answer
A
Slide 1-22
Representations of Motion
Slide 2-9
Motion diagram (student walking to school)
Table of data Graph
Here is a motion diagram of a car moving along a straight stretch of road:
Which of the following velocity-versus-time graphs matches this motion diagram?
Checking Understanding 2
A.
Slide 2-13
B. C. D.
Here is a motion diagram of a car moving along a straight stretch of road:
Which of the following velocity-versus-time graphs matches this motion diagram?
Slide 2-14
C.
Answer
Checking Understanding 3
Slide 2-15
A graph of position versus time for a basketball player moving down the court appears like so:
Which of the following velocity graphs matches the above position graph?
A. B. C. D.
Slide 2-16
A graph of position versus time for a basketball player moving down the court appears like so:
Which of the following velocity graphs matches the above position graph?
C.
Answer
Acceleration
Acceleration is:
• The rate of change of velocity
• The slope of a velocity-versus-time graph
Slide 2-20
A ball is released from rest at the point shown on the incline and speeds up. It then rolls onto a level section of track at constant speed, and then rolls onto a second incline with the same slope as the first where it slows down. The diagram below shows the location of the ball at several instants in time. NOTE: THIS IS NOT A STROBE PHOTOGRAPH OR MOTION DIAGRAM.
1. Describe the motion of the ball as it moves from left to right2. Determine the average velocity of the ball from t = 2.1 s to t = 3.6 s.3. Determine the average speed of the ball from t = 0.6 s to t = 5.1 s.4. Determine the average acceleration, ax, of the ball as it goes up the 2nd
incline (from t = 3.6 s to t = 5.1 s).
Ball on Ramps (From an Exam)
Question
4. Velocity vectors point
A. in the same direction as displacement vectors.
B. in the opposite direction as displacement vectors.
C. perpendicular to displacement vectors.
D. in the same direction as acceleration vectors.
E. Velocity is not represented by a vector.
Slide 1-8
4. Velocity vectors point
A. in the same direction as displacement vectors.
Slide 1-9
Answer
Vectors
Slide 3-9
Adding Vectors Graphically
Slide 1-33
Adding Displacement Vectors
Slide 1-31
Example: Adding Displacement Vectors
Jenny runs 1 mi to the northeast, then 1 mi south. Graphically find her net displacement.
Slide 1-32
Slide 1-7
Adding Vectors
Find the following resultants graphically
Vector Subtraction
Slide 3-10
Slide 3-11
Acceleration Vectors
Checking Understanding
Slide 3-13
Which of the vectors below best represents the vector sum P + Q?
Slide 3-14
Which of the vectors below best represents the vector sum P + Q?
Answer
Checking Understanding
Slide 3-15
Which of the vectors below best represents the difference P – Q?
Slide 3-16
Which of the vectors below best represents the difference P – Q?
Answer
A ball is released from rest at the point shown on the incline and speeds up. It then rolls onto a level section of track at constant speed, and then rolls onto a second incline with the same slope as the first where it slows down. The diagram below shows the location of the ball at several instants in time. NOTE: THIS IS NOT A STROBE PHOTOGRAPH OR MOTION DIAGRAM.
• Draw a motion diagram for the following motion• On the diagram above, use a delta v diagram to help draw an arrow
indicating the direction of the acceleration of the ball at point A.
Ball on Ramps (From an Exam)
QuickTime™ and a decompressor
are needed to see this picture.
Example: Velocity Vectors
Jake throws a ball at a 60° angle, measured from the horizontal. The ball is caught by Jim. Draw a motion diagram of the ball with velocity vectors.
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