physics 534 chapter 7
TRANSCRIPT
8/8/2019 Physics 534 Chapter 7
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Simple Motion
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Motion Kinematics deals with
describing the motion of objects.
Dynamics is the study of why
objects move as they do.
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T
ypes of Motion Rectilinear: Motion in a straight
line path. E.g. an elevator.
Curvilinear: Motion in a curvedpath. A ball being thrown.
Random: A combination of theabove. A leaf in the wind.
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O
bservable Motion Motion can either be seen
(observable) or be sensed(non-observable).
E.g. Gas in the gas hose?
E.g. Doppler effect of a car ?
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V
ectors and Scalars A vector quantity has a size,
unit and direction. E.g. 5 km/h [N] (North) A scalar quantity has a size
and unit. E.g. 16 N (Newtons)
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Activity Page 164, Q.1
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Distance and Displacement Distance travelled depends on
position.
Distance is a scalar quantity.
It is always positive.
E.g. d = 5 km
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Distance and Displacement Displacement depends on the
new position compared to theold position.
Displacement is a vector
quantity. E.g. d = 5 km North
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Activity Page 166, Q. 1- 6
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V
ector Diagrams We can show vectors as
arrows in diagrams.
We add vectors tip to tail. Vector +Vector B = Vector B + Vector
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V
ector Diagrams
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T
ools for Solving You can use diagrams;
Pythagoras c2
= a2
+ b2;
Sine Law
Cosine Law SOHCAHTO A
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Activity Page 169. Q. 1 ± 4
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Summary Some motions can be seen
easily; other motions must beobserved using other sensesor devices.
The trajectory is the path of amoving object.
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Summary Vector quantities have
magnitude and direction.
Scalar quantities only havemagnitude.
Displacement, or change inposition, is a vector quantity.
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Summary Distance, the path length, is a
scalar quantity.
Add vectors tip to tail.
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Exam Question
Donald is sitting beside a railway track watching railway cars moving to his right at a constant
speed. Suddenly he notices a person on one of the cars in front of him throw a metal bolt
directly upward.
What is the trajectory of the metal bolt that Donald will see? (Disregard air resistance.)
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Exam QuestionWhile sitting on a park bench, Ken sees a cyclist ride by in front of him in a straight line at aconstant velocity. He observes the trajectory of the reflector fastened to a spoke of the frontwheel, as illustrated below.
Directionof the bicycle
Reflector
Which of the following represents the trajectory observed by Ken?
A)
B)
C)
D)
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Activity Do Q. 1 ± 8 on p. 170 -1