**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)