Physics 534 Chapter 7

8/8/2019 Physics 534 Chapter 7

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Simple Motion



Motion Kinematics deals with

describing the motion of objects.

Dynamics is the study of why

objects move as they do.



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.



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 ?



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)



Activity Page 164, Q.1



Distance and Displacement Distance travelled depends on

position.

Distance is a scalar quantity.

It is always positive.

E.g. d = 5 km



Distance and Displacement Displacement depends on the

new position compared to theold position.

Displacement is a vector

quantity. E.g. d = 5 km North



Activity Page 166, Q. 1- 6



V

ector Diagrams We can show vectors as

arrows in diagrams.

We add vectors tip to tail. Vector +Vector B = Vector B + Vector



V

ector Diagrams



T

ools for Solving You can use diagrams;

Pythagoras c2

= a2

+ b2;

Sine Law

Cosine Law SOHCAHTO A



Activity Page 169. Q. 1 ± 4



Summary Some motions can be seen

easily; other motions must beobserved using other sensesor devices.

The trajectory is the path of amoving object.



Summary Vector quantities have

magnitude and direction.

Scalar quantities only havemagnitude.

Displacement, or change inposition, is a vector quantity.



Summary Distance, the path length, is a

scalar quantity.

Add vectors tip to tail.



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.)



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)



Activity Do Q. 1 ± 8 on p. 170 -1

Physics 534 Chapter 7

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