AP Physics - Intro
What is Physics?
Physics is the branch of knowledge that studies the physical world
A mathematical science
The search for understanding
The study of matter and energy
Best Answer
Who are Physicists?
Physicists are people who investigate the physical world
Science
What is Science?
Knowledge, the act of knowing
Who are Scientists?
People who look at the world around them with questioning eyes
They ask many questions
Hope for powerful explanations that describe more than one phenomenon and lead to a better understanding of the universe
Need for Scientist/Physicist
To improve the standards of living
To solve the many problems that we encounter
Require a common language for comparison of data
Greek philosophers (4th and 5th century BC)
Based their findings on observations and then fitting them into a logical framework or theory
Europeans (16th Century)
At first they accepted the no experiment Greek philosophy
Galileo Galilei (1564-1642)
First scientist to publicly state that knowledge must be based on observations and experiments
To prove the Greeks wrong he developed a systematic method of observation, experimentation and analysis
The Father of the Scientific Method
Scientific Method
Identify the problem
Gather data
Form a hypothesis
Test hypothesis
Form conclusion
**Not only way to learn
English System - British System
Metric System - S.I System
1795 French scientist developed
Easy to Use
Based on powers of 10
Decimal System
Standards were determined by international committee because of need for worldwide standards
Standards for mass, length, volume and time are kept by N.I.S.T.
Standard Units
Mass - Kilogram (kg)
The amount of matter in an object
Length - Meter (m)
Time - Second (s)
Volume - Liter (L)
How much space an object takes up
Derived Units
Standard units used together to describe other quantities
Speed = distance / time = m / s
Density = mass / volume = Kg / L
Volume = length * width * height = m3
T G M K H D megs d c m µ n p
Tera = T
1012
Giga = G
109
Mega = M
1,000,000 = 106
Kilo = K
1,000 = 103
Hecto = H
100 = 102
Decka = D, da, dk
10
Base Units
m, l, g, s
1
Deci = d
1/10
Centi = c
1/100 = 10-2
Milli = m
1/1,000 = 10-3
Micro = µ
1/1,000,000 = 10-6
Nano = n
10-9
Pica = p
10-12
If the digit to be dropped is 4 or less, just drop it
21.3 → 21
1.24 → 1.2
If the digit to be dropped is 6 or greater, increase the digit to the left by one
21.6 → 22
1.26 → 1.3
If the digit to be dropped is 5, increase the digit to the left if it is odd. Do not increase the number to the left if it is even
21.5 → 22
24.5 → 24
Expressing large and small numbers in short hand method by expressing the decimal places as powers of 10
M * 10n
M is the whole number and n is the power of 10
Examples of large numbers
6,000,000,000,000,000,000,000,000 kg - Mass of Earth
6 × 1024 kg
300000000 m/s - speed of light
3 * 108 m/s
Examples of small numbers
.000000000000000000000000000000911 kg - Mass of an electron
9.11 * 10-31 kg
Rules for Writing Scientific Notation
Move the decimal point to get only one nonzero number to the left of the decimal
1 <= M >= 9
The whole number must be between 1 and 9
2,000 = 2 * 103
.0003 = 3 * 10-3
Scientific Notation Rules for Adding and Subtracting
Numbers must have same units
Numbers must have same power of 10
Precision must be same (round)
Add or subtract the whole number parts and include the common power of 10 and units
Examples
4 * 108 m + 3 * 108 m = 7 * 108 m
6.2 * 10-3 m - 2.8 * 10-3 m = 3.4 * 10-3 m
4.0 * 106 m + 3.1 * 105 m
4.0 * 106 m + 0.3 * 106 m = 4.3 * 106 m
Any measurement is inaccurate to some degree. The inaccuracy stems from several factors. The precision of any measuring device is limited. The person doing the measurement may introduce error. The experimental technique may be faulty. Because a measurement contains some degree of inaccuracy, the number of digits that are valid for the measurement are also limited.
The digits which indicates the number of units we are reasonably sure of having counted in making a measurement are significant figures.
The more precise the instrument, the more significant figures you will have.
Significant Figure Rules
All nonzero digits are significant
3659 has 4 sig figs
All zeros between two nonzero digits are significant
406 has 3 sig figs
4006 has 4 sig figs
All zeros to the left of an understood decimal but to the right of a nonzero digit are not significant
6000 has 1 sig fig
All zeros to the left of an expressed decimal point and to the right of a nonzero digit are significant
6000__.__ has 4 sig figs
All zeros to the right of a decimal point but to the left of a nonzero digit are not significant
.0214 has 3 sig figs
All zeros to the right of both the decimal point and a nonzero digit are significant
.021400 has 5 sig figs
All numbers in front of the power of 10 in scientific notation are significant
3.014 * 10^5 has 4 sig figs
Significant Figure Rules for Addition and Subtraction
All measurements must be in the same units
The answer obtained can not be any more precise than the least precise measurement used in the problem
Any measurement which has significant figures in a column of numbers which contains a non-significant figure should be rounded off until every number in a column is a significant figure
Add or Subtract
Round before adding or subtracting
Significant Figure Rules for Multiplying and Dividing
The answer can’t have more significant figures than the number in the problem having the least number of significant figures
6.134 ft (4 sig figs) * 2.0 ft (2 sig figs) * 1.01 ft (2 sig figs) = 12 ft
Answer can only have 2 sig figs because it is the least number
Graph
a visual display of data that shows a relationship between the dependent and independent variables
Dependent Variable - “Measure”
Changes based on the independent variable
Independent Variable - “Control”
Is not affected by the dependent variable
Slope
(y2 - y1) / (x2 - x1)
Relationships
correlations between data on a graph
Direct relationship
Both X and Y increase
Direct Linear
y = mx + b
Direct Power
y = mx2
Direct Root
y = m √x
Indirect relationship
As X increases, Y decreases
Indirect Inverse
y = m/x
Inverse Power ( “Inverse Square” )
y = m / x2
Inverse Root
y = m / √x
What is Physics?
Physics is the branch of knowledge that studies the physical world
A mathematical science
The search for understanding
The study of matter and energy
Best Answer
Who are Physicists?
Physicists are people who investigate the physical world
Science
What is Science?
Knowledge, the act of knowing
Who are Scientists?
People who look at the world around them with questioning eyes
They ask many questions
Hope for powerful explanations that describe more than one phenomenon and lead to a better understanding of the universe
Need for Scientist/Physicist
To improve the standards of living
To solve the many problems that we encounter
Require a common language for comparison of data
Greek philosophers (4th and 5th century BC)
Based their findings on observations and then fitting them into a logical framework or theory
Europeans (16th Century)
At first they accepted the no experiment Greek philosophy
Galileo Galilei (1564-1642)
First scientist to publicly state that knowledge must be based on observations and experiments
To prove the Greeks wrong he developed a systematic method of observation, experimentation and analysis
The Father of the Scientific Method
Scientific Method
Identify the problem
Gather data
Form a hypothesis
Test hypothesis
Form conclusion
**Not only way to learn
English System - British System
Metric System - S.I System
1795 French scientist developed
Easy to Use
Based on powers of 10
Decimal System
Standards were determined by international committee because of need for worldwide standards
Standards for mass, length, volume and time are kept by N.I.S.T.
Standard Units
Mass - Kilogram (kg)
The amount of matter in an object
Length - Meter (m)
Time - Second (s)
Volume - Liter (L)
How much space an object takes up
Derived Units
Standard units used together to describe other quantities
Speed = distance / time = m / s
Density = mass / volume = Kg / L
Volume = length * width * height = m3
T G M K H D megs d c m µ n p
Tera = T
1012
Giga = G
109
Mega = M
1,000,000 = 106
Kilo = K
1,000 = 103
Hecto = H
100 = 102
Decka = D, da, dk
10
Base Units
m, l, g, s
1
Deci = d
1/10
Centi = c
1/100 = 10-2
Milli = m
1/1,000 = 10-3
Micro = µ
1/1,000,000 = 10-6
Nano = n
10-9
Pica = p
10-12
If the digit to be dropped is 4 or less, just drop it
21.3 → 21
1.24 → 1.2
If the digit to be dropped is 6 or greater, increase the digit to the left by one
21.6 → 22
1.26 → 1.3
If the digit to be dropped is 5, increase the digit to the left if it is odd. Do not increase the number to the left if it is even
21.5 → 22
24.5 → 24
Expressing large and small numbers in short hand method by expressing the decimal places as powers of 10
M * 10n
M is the whole number and n is the power of 10
Examples of large numbers
6,000,000,000,000,000,000,000,000 kg - Mass of Earth
6 × 1024 kg
300000000 m/s - speed of light
3 * 108 m/s
Examples of small numbers
.000000000000000000000000000000911 kg - Mass of an electron
9.11 * 10-31 kg
Rules for Writing Scientific Notation
Move the decimal point to get only one nonzero number to the left of the decimal
1 <= M >= 9
The whole number must be between 1 and 9
2,000 = 2 * 103
.0003 = 3 * 10-3
Scientific Notation Rules for Adding and Subtracting
Numbers must have same units
Numbers must have same power of 10
Precision must be same (round)
Add or subtract the whole number parts and include the common power of 10 and units
Examples
4 * 108 m + 3 * 108 m = 7 * 108 m
6.2 * 10-3 m - 2.8 * 10-3 m = 3.4 * 10-3 m
4.0 * 106 m + 3.1 * 105 m
4.0 * 106 m + 0.3 * 106 m = 4.3 * 106 m
Any measurement is inaccurate to some degree. The inaccuracy stems from several factors. The precision of any measuring device is limited. The person doing the measurement may introduce error. The experimental technique may be faulty. Because a measurement contains some degree of inaccuracy, the number of digits that are valid for the measurement are also limited.
The digits which indicates the number of units we are reasonably sure of having counted in making a measurement are significant figures.
The more precise the instrument, the more significant figures you will have.
Significant Figure Rules
All nonzero digits are significant
3659 has 4 sig figs
All zeros between two nonzero digits are significant
406 has 3 sig figs
4006 has 4 sig figs
All zeros to the left of an understood decimal but to the right of a nonzero digit are not significant
6000 has 1 sig fig
All zeros to the left of an expressed decimal point and to the right of a nonzero digit are significant
6000__.__ has 4 sig figs
All zeros to the right of a decimal point but to the left of a nonzero digit are not significant
.0214 has 3 sig figs
All zeros to the right of both the decimal point and a nonzero digit are significant
.021400 has 5 sig figs
All numbers in front of the power of 10 in scientific notation are significant
3.014 * 10^5 has 4 sig figs
Significant Figure Rules for Addition and Subtraction
All measurements must be in the same units
The answer obtained can not be any more precise than the least precise measurement used in the problem
Any measurement which has significant figures in a column of numbers which contains a non-significant figure should be rounded off until every number in a column is a significant figure
Add or Subtract
Round before adding or subtracting
Significant Figure Rules for Multiplying and Dividing
The answer can’t have more significant figures than the number in the problem having the least number of significant figures
6.134 ft (4 sig figs) * 2.0 ft (2 sig figs) * 1.01 ft (2 sig figs) = 12 ft
Answer can only have 2 sig figs because it is the least number
Graph
a visual display of data that shows a relationship between the dependent and independent variables
Dependent Variable - “Measure”
Changes based on the independent variable
Independent Variable - “Control”
Is not affected by the dependent variable
Slope
(y2 - y1) / (x2 - x1)
Relationships
correlations between data on a graph
Direct relationship
Both X and Y increase
Direct Linear
y = mx + b
Direct Power
y = mx2
Direct Root
y = m √x
Indirect relationship
As X increases, Y decreases
Indirect Inverse
y = m/x
Inverse Power ( “Inverse Square” )
y = m / x2
Inverse Root
y = m / √x
