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Motion (Physics Unit):. Chapters 9-12 . Converting to Scientific Notation:. Rule 1: Move the decimal to where there is one nonzero digit to the left of the decimal point. (This creates a number between 1 and 10)
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Motion (Physics Unit): Chapters 9-12
Converting to Scientific Notation: • Rule 1: Move the decimal to where there is one nonzero digit to the left of the decimal point. (This creates a number between 1 and 10) • Rule 2: If the decimal point is moved to the left, the exponent is positive. • Rule 3: If the decimal point is moved to the right, the exponent is negative.
Scientific notation Standard form: • Move the decimal to either the left (if the exponent is negative), or to the right (if it is positive), the number of spaces indicated by the exponent. • Ex: 2.38 x 10^-5 becomes…. • 0.0000238
Significant figures: (1) All nonzero digits are significant: 1.234 g has 4 sig. figs. (2) Zeroes between nonzero digits are significant: 1002 kg has 4 significant figures (3) Leading zeros to the left of the first nonzero digits are not significant; they merely indicate place value: 0.001 oC has only 1 significant figure (4) Trailing zeroes that are also to the right of a decimal are significant: 0.0230 mL has 3 significant figures,
Metric Conversions: • 1km = 1000m, 1m = 100cm, 1cm =10mm • *The meter is the base unit for distance in physics, that means physicists (and physics students) convert distances to meters when doing calculations: • “kilo” means “thousand” • “centi” means “hundred” • “milli” means “thousandth”
Converting units of time: • 60 seconds = 1 minute, 60 minutes = 1 hour, try these: • 15 mins = _______ hours 300 secs = ______min • 2.0 hours = _______ min 0.5 hours = ______min • 38 min = _______ sec 42 min = ________hrs • 3.5 hours = ______ sec 160 sec = _______ min • 1.24 hours = _____ min 90 min = _______ sec
Calculating speed: • Speed = Distance Time Average speed = Total distance, divided by total time. Express your answers in the proper units, such as: Kilometers per hour (km/h), miles per hour (mph), meters per hour (m/h), meters per second (m/s), centimeters per second (cm/s), feet per second (f.p.s.) etc *m/s is the base unit for speed/velocity in physics.
Distance-Time Graphs: • *Speed can be represented by the letter “v” for velocity, which is the same as speed when you are travelling in a straight line (assumed in these questions). • The ‘s in the equation represent “change in”. • Speed can be determined from the slope of a line of best fit from a distance-time graph. • See examples on pages 364 and 365. • # 5 (a-f) on page 365 • Now try # 11 and 12 (a and b only) on pages 376-377.
Speed vs velocity: • Distance = how far an object travels. • Displacement = how far away an object is from where it started. *If you run one lap around a circular ¼ mile track, your distance traveled is 1/4mile, your displacement would be 0.
Speed vs velocity: • Speed is a measurement of magnitude (distance) only; it does not take into account direction. It is called a scalar quantity. • Velocity is a measurement of both magnitude and direction (displacement). It is therefore called a vector quantity.