Physics Study Guide. Chapter 2 Sections 1 and 2. Dimensional Analysis. Method of using equivalence statements to convert from one unit to another Example – Convert 12 feet into yards. 12 ft x (yd / 3 ft) = 4 yd
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Physics Study Guide Chapter 2 Sections 1 and 2
DimensionalAnalysis • Method of using equivalence statements to convert from one unit to another • Example – Convert 12 feet into yards. 12 ft x (yd / 3 ft) = 4 yd • Always put on the bottom of the fraction what you wish to cancel and put what you want on the top.
DimensionalAnalysis • Convert 14.7 days to months. • Convert 500 kg to Mg. • Convert 5 μm to m. • Convert 4500 ps to ns. • The area of an object is 137 km2. Express this area in m2.
Scientific Notation • Easier method of writing really small or really large numbers • Ex – 3,400,000 is the same as 3.4 x 106 • Ex – 0.00047 is the same as 4.7 x 10-4
Scientific Notation • Express 53,200,000 in scientific notation. • Express 0.0004 in scientific notation. • Express 57.52 in scientific notation. • Express 0.00000056 in scientific notation.
Chapter 2 Sections 1-2 • Frame of reference A coordinate system for specifying the precise location of objects in space No reference frame is more “correct” than another
Chapter 2 Sections 1-2 • Distance Total path length traversed in moving from one location to another Scalar quantity
Chapter 2 Sections 1-2 • Scalar quantity A quantity with only magnitude, or size Examples – time, temperature, mass, distance
Chapter 2 Sections 1-2 • Displacement Change in position of an object Measured as straight line drawn from initial to final position Δx = xf – xi where Δ (delta) means change
Chapter 2 Sections 1-2 Doesn’t usually equal distance Should include description of direction Vector quantity
Vector Quantity A quantity with both magnitude (or size) and direction Examples – force, displacement, velocity
Chapter 2 Sections 1-2 You make a trip to the store and then return home. What is your displacement?
Chapter 2 Sections 1-2 • Average speed Actual distance covered divided by the corresponding change in time Avg speed = distance time SI unit of speed is m/s Scalar quantity
Chapter 2 Sections 1-2 • Average velocity Total displacement divided by the corresponding change in time Avg velocity = displacement time V = Δx Δt SI unit of velocity is m/s Vector quantity
Chapter 2 Sections 1-2 You drive to a friend’s house 370 km to the west. If you left at 10 am and arrived at 3 pm, what is your average velocity?
Chapter 2 Sections 1-2 A car travels 100 km. If the first half of the distance is driven at 50 km/h and the second half is driven at 100 km/h, what is the average velocity?
Chapter 2 Sections 1-2 Heather and Matthew walk eastward with a velocity of 0.98 m/s. If it takes them 34 min to walk to the store, how far have they walked?
Chapter 2 Sections 1-2 If Joe rides south on his bicycle in a straight line for 15 min with an average speed of 12.5 km/h, how far has he ridden?
Chapter 2 Sections 1-2 Simpson drives his car with an average velocity of 48 km/h to the east. How long will it take him to drive 144 km on a straight highway?
Chapter 2 Sections 1-2 A bus travels 280 km south along a straight path with an average velocity of 88 km/h to the south. The bus stops for 24 min, then it travels 210 km south with an average velocity of 75 km/h to the south. How long does the total trip last? What is the average velocity for the total trip?
Chapter 2 Sections 1-2 • Instantaneous velocity Velocity of an object at some specific point Defined mathematically as v = lim (Δx / Δt)