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Discover the basics of physics, from mass and energy to dimensional analysis and significant figures. Learn about scientific notation, measurement systems, and mathematical operations with examples and practice problems.
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PHYSICS Introduction
HOT SITES • WWW.GEOCITIES.COM/SHPMRWILHELM • SCIENCE.GLENCOE.COM
Mass • The measure of a body’s inertia M m
Inertia • The resistance to any change in a body’s motion. M m V V
Weight • The amount of gravitational force acting on a body. w w
Force • A push or pull on a body N F W f
ENERGY • THE CAPACITY TO DO MECHANICAL WORK
KINETIC ENERGY • THE ENERGY A BODY HAS DUE TO ITS MOTION
POTENTIAL ENERGY • THE ENERGY A BODY HAS DUE TO ITS POSITION OR CONFIGURATION
THE LAW OF CONSERVATION OF ENERGY • THE TOTAL AMOUNT OF ENERGY IN A CLOSED SYSTEM IS CONSTANT. Σ Ei = Σ Ef
FUNDAMENTAL QUANTITIES BASIC MEASUREMENTS FROM WHICH ALL OTHERS ARE DERIVED. Mass [M] Electric Charge [Q] Length [L] Luminous Intensity [I] Time [T] Temperature [t0] Amount of substance [N]
DERIVED QUANTITIES Speed [L]/[T] Acceleration [L]/[T]2 Density [M]/[L]3 Area [L]2 Force [M][L]/[T]2 Volume [L]3
METRIC PREFIXES Giga (G) 109 Deci (d)10-1 Mega (M) 106Centi (c) 10-2 Kilo (K) 103Milli (m) 10-3 Hecto (H) 102Micro (μ) 10-6 Deka (Da) 101Nano (n) 10-9 {basic unit}100Pico (p) 10-12
DIMENSIONAL ANALYSIS IN CONVERSIONS{_______} Numerator equals denominator 6.0 ft = _____ in 12 in 6.0 ft ( ) = 72 in 1 ft 4.2 oz = _____ lb 1 lb _ 4.2 oz ( ) = 0.26 lb 16 oz
MORE D. A. 6.0 min = _____hr 1 hr 6.0 min ( ) = 0.10 hr 60 min 7.0 days = _____ s 24 hr 60 min 60 s 7.0 days ( ) ( ) ( )= 604,800 s 1 day 1 min 1 hr
TRY THESE CONVERSIONS 1 mile = _____in 12 ft2 = ______in2 100 in3 = ______ft3 25 mile/hr = _____ft/s
METRIC CONVERSIONS 15 m = _____cm 230,000,000 μg =_____g 25 m2 = _____km2 11 g/cm3 = _____kg/m3
SIGNIFICANT FIGURES Significant figures are those digits in a measurement that are known with certainty PLUS the first digit that is uncertain (estimated). I I I I I I I I I I I I I I I I I I I I I I I 23 24 25 The digits 23.6 are known for certain --- the next digit is estimated to be 0.03 --- record your measurement as 23.63
More Measurements • --10 • - • -9 • - • -8 • - • -7 • - • -6 • - • -5 I I I I I I I I I I I I 97.6 97.8 98.0 98.2 98.4 98.6 I I I I I I I I I I I I 60 70 80 90 100 110
Mathematical Operations with Sig Figs ADDITION AND SUBTRACTION • The place holder of your last significant digit is • determined by your least precise measurement. • The least precise measurement will have its • last significant digit furthest to the left. 2500.8 mg + 20,279 mg + 0.8765 mg = 22,781 mg
Mathematical Operations with Sig Figs Multiplication and Division • That measurement having the fewest number • of significant figures determines the number • of significant figures in the answer. 41,000 ft 20,400 ft/s X 2.0 s = 2,500,000 g 500.0 cm3 = 5000 g/cm3
ROUNDING If the number following the last significant digit is greater than 5, round up. 0.007892600 rounds to 0.007893 0.007892501 rounds to 0.007893 (note that it is more than half-way between 2 and 3) If the number following the last significant digit is less than 5, round down. 0.007892400 rounds to 0.007892
ROUNDING If the number following the last significant digit is exactly 5, round so that the last significant figure is even. 0.007892500 rounds to 0.007892 0.007897500 rounds to 0.007898 This method prevents experimental results from being skewed up or down.
SCIENTIFIC NOTATION Format: M X 10n • M is a decimal number having a single • non-zero digit to the left of the decimal. {NOTE : M only contains the significant digits} • n is the integer exponent on the 10. { } NOTE : Positive n a value > 1 Negative n a value < 1
SCIENTIFIC NOTATION EXAMPLES 570,300,000 cm = 5.703 X 108 cm 0.000 002 05 g = 2.05 X 10-6 g ( see more practice on page 20 of your text )
Adding/subtracting using Sci Not • Convert all numbers to make exponents • all agree with the largest. (if needed) (2) Add/subtract the coefficients normally. (3) Convert back to scientific notation. (if needed)
Multiplying/dividing using Sci Not (a) Mult/div coefficients normally. (b) ADD exponents if multiplying. SUBTRACT exponents if dividing. (c) Convert back to scientific notation. (if needed)
105 _g_ _g_ g 3.0 _3.0 X105 g___ = X X cm3 cm3 cm3 9.0 10-2 9.0 X10-2 cm3 Practice Problems 5.36 X10-1 kg - 7.40 X10-2 kg 5.36 X10-1 kg - 0.740 X10-1 kg 4.62 X10-1 kg 106 x 3.3 = 107 0.33 X
GRAPHS Line graphs – used to show the relationship between two quantities when there is a mathematical relationship between them. Direct proportion→ straight line Inverse proportion → hyperbola Quadratic relationship → parabola