Welcome to Chapter 1 AP PHYSICS …do you remember… Theories Hypothesis Law Models.
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Transcript of Welcome to Chapter 1 AP PHYSICS …do you remember… Theories Hypothesis Law Models.
How about the SI system?...
• How big is 106 volts…that’s shocking!
• How small are cells? Nano-nano
• Know your prefixes?
Significant Digits?
• What’s significant about that?
• Saved by zero?
• Scienctific ‘know’ tation?
• …know your sd rules?
Chapter 1…
• The scientific ‘methods’…
• Decide on a problem…
• Develop a hypothesis… If…then…
• Test a hypothesis…experimentation…
• Observe…record…conclude
• Repeat until a hypothesis becomes a theory…where do laws fit in?
Theory, Law, Principle…
• A theory explains how things work…
• …a theory can never be absolutely proven.
• A law is a concise, but general statement that describes how nature behaves…
• A less general statement is called a principle…the line is a blur…
Measurement and Uncertainty
• Every measurement has uncertainty…
• Estimated uncertainty is your + or – number…
• Percent uncertainty is stated as a %...
Significant Digits
• Non-zero numbers are always significant…• Trailing zeros left of a decimal are not sd…• Leading zeros to the right of a decimal are
sd…• Trailing zeros to the right of a decimal are
sd…• Sandwiched zeros are significant…
SI System
• The standard unit of length is the meter…• The standard unit of time is the second…• The standard unit of mass is the kg…• U is the unified atomic mass unit…• 1u = 1.66 x10-27kg• MKS meter-kilogram-second system• Cgs is the centimeter, gram, second
system
Conversions/ Dimensional Analysis
• Simple units…
• Complex units…
• System to system conversion factors…