Physics – Premed Windsor University School of Medicine and Health Sciences J.C. Rowe Course...

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Transcript of Physics – Premed Windsor University School of Medicine and Health Sciences J.C. Rowe Course...

Physics – Premed Windsor University School of Medicine and

Health Sciences

J.C. RoweCourse Instructor.

Pre Med – PhysicsChapter 0 - Intro

There is more to lectures than the power point slides!

Engage your mind - go beyond the class!

PHYICSPHYICS

What is Physics ?

• Def’d-1: analysis of nature & how the universe behaves

• Def’d-2: the scientific study of matter and energy and how they interact with each other

Involves:• motion, heat, light, electricity, magnetism,

atomic structure, gravity etc..

How Does The Natural World Function?

Fundamental Questions e.g:

•How did the universe begin?•How will the universe change in the future?•How / why does the Sun keep on shining?•What are the basic building blocks of matter?•How does matter exist?

UNITS (Systéme Internationale)Dimension SI (mks) Unit Definition

Length meters (m) Distance traveled by light in 1/(299,792,458) s

Mass kilogram (kg) Mass of a specific platinum-iridium allow cylinder kept by Intl. Bureau of Weights and Measures at Sèvres, France

Time seconds (s) 9,192,631,700 oscillations of cesium atom

Prefixes

In addition to mks units, standard prefixes can be

used, e.g., cm, mm, m, nm

Significant Figures: Division

Find the value of 6.49m divided by 5.1037sCalculator gives 1.271626467 !Too many figures. FALSE AccuracyOnly 3 significant figures. Why? 1.27m/s

Number # Significant Figures Rule(s)

48,923 5 1

3.967 4 1

900.06 5 1,2,4

0.0004 (= 4 E-4) 1 1,4

8.1000 5 1,3

501.040 6 1,2,3,4

3,000,000 (= 3 E+6) 1 1

10.0 (= 1.00 E+1) 3 1,3,4

Estimate the number of times a human heart beats during its lifetime.

Estimate - a typical heart beats ~60 times per minute:

ESTIMATION

2.4 x 109 beats/lifetime

Length:DistanceDistance Length (m)Length (m)Radius of visible universe 1 x 1026

To Andromeda Galaxy 2 x 1022

To nearest star 4 x 1016

Earth to Sun 1.5 x 1011

Radius of Earth 6.4 x 106

Sears Tower 4.5 x 102

Football field 1.0 x 102

Tall person 2 x 100

Thickness of paper 1 x 10-4

Wavelength of blue light 4 x 10-7

Diameter of hydrogen atom 1 x 10-10

Diameter of proton 1 x 10-15

Time:

IntervalInterval Time (s)Time (s)Age of universe 5 x 1017

Age of Grand Canyon 3 x 1014

32 years 1 x 109

One year 3.2 x 107

One hour 3.6 x 103

Light travel from Earth to Moon 1.3 x 100

One cycle of guitar A string 2 x 10-3

One cycle of FM radio wave 6 x 10-8

Lifetime of neutral pi meson 1 x 10-16

Lifetime of top quark 4 x 10-25

Mass:

ObjectObject Mass (kg)Mass (kg)Milky Way Galaxy 4 x 1041

Sun 2 x 1030

Earth 6 x 1024

Boeing 747 4 x 105

Car 1 x 103

Physics Student 7 x 101

Dust particle 1 x 10-9

Top quark 3 x 10-25

Proton 2 x 10-27

Electron 9 x 10-31

Neutrino 1 x 10-38

Conversion of Units• Example:

The Distance from point A to the Andromeda Nebula is 2 x 106 light years. What is the distance in km ?

1. Conversion factor: 1 ly = 9.5 x 1012 km 2. Insert conversion factor: d = 2 x 106 ly & 1 ly = 9.5 x 1012 km = 2 x 106 x 9.5 x 1012 km = 1.9 x 1019 km

Remember: 10a x10b = 10a+b

10a / 10b = 10a-b

Example:

• If the speed limit on the German autobahn is 150 kilometers/hour. What is the speed limit in metres/hour ?

• What is the speed limit in mile/ hour?

Lecture 1, Activity

A very good fastball pitcher can throw the ball 100 mi/hr. What is the ball speed in m/s? (Answer in 3 significant figures)

1 - 450 m/s2 - 44.7 m/s3 - 0.045 m/s4 – 28.1 m/s5 - 28.2 m/s

correct

Dimensional Analysis• Dimension indicates the nature of a physical quantity or the

type of unit.

Example:Dimension of distance is length : [L]Unit of distance is m , km, miles, …

Note:Dimensions of left-hand side and right-hand side of anequation have always to be the same, e.g. when you start witha quantity of dimension length you have to finish with oneof dimension length.

Powerful check of your computation !

TrigonometryDefinition of sine, cosine and tangent:

Sin = opp/hyp

Cos = adj/hyp

Tan = opp/adj

Pythagorean Theorem: c2 = a2 + b2

Physics Applied • The Lunar Dome

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