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Write these down while you wait: 1 hr = 60 min = 3600 sec 1 km = 1000 m .6214 mile 1 mile = 5280 ft = 1760 yards 1609 m 1 m 3.281 ft 1 yard = 3 feet Shortcuts: 1 m/s = 3.6 km/hr 2.237 mph, (mph = miles/hour) 1 mph 1.47 f/s (1.46666666…) 1 f/s .682 mph (.6818181818…)
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Write these down while you wait: 1 hr = 60 min = 3600 sec 1 km = 1000 m .6214 mile 1 mile = 5280 ft = 1760 yards 1609 m 1 m 3.281 ft 1 yard = 3 feet Shortcuts: 1 m/s = 3.6 km/hr 2.237 mph, (mph = miles/hour) 1 mph 1.47 f/s (1.46666666…) 1 f/s .682 mph (.6818181818…) Answer This Question: How many feet per second is 30 mph? (use any method you want – including help from others – but have an answer)
Write these down while you wait: 1 hr = 60 min = 3600 sec 1 km = 1000 m .6214 mile 1 mile = 5280 ft = 1760 yards 1609 m 1 m 3.281 ft 1 yard = 3 feet Shortcuts: 1 m/s = 3.6 km/hr 2.237 mph, (mph = miles/hour) 1 mph 1.47 f/s (1.46666666…) 1 f/s .682 mph (.6818181818…) Answer This Question: How many feet per second is 30 mph? (use any method you want – including help from others – but have an answer) (30 mph)(1.4666666) = 44 ft/s (30 mi)(5280 ft)(1 hr) = 44 ft/s ( hr )( 1 mi )(3600 s)
Dimensional AnalysisContents: • Handy things to know • Ways to convert • Whiteboard practice
Unit cancellation • Calculator’s built in (TI 85/86) • Conversion factors • Google Ways to convert units: • Unit cancellation: • 30. mph to ft/s: • 30. mi(5280 ft)( 1 hr ) • hr ( 1 mi )(3600 s) = 44 f/s (note the units canceling) • Calculator (TI 85/86) • 2ndCONV, MORE, MORE, SPEED, 30 mi/hr > ft/s • Conversion factor: • 30. mph to ft/s: (1 mph = 1.47 f/s) • 30. mph x (1.47) = 44.1 = 44 ft/s • (slightly off - what’s the “real” conversion factor?) • Google: • Type 30. mph in ft/s into the search bar (text it?) TOC
Whiteboards: Conversions 1 | 2 | 3 | 4 | 5 TOC
Convert 32 mile/hour to feet/second 5280 ft = 1 mi 3600 s = 1 hr 32 mi(5280 ft)( 1 hr ) = 46.933333 hr ( 1 mi )(3600 s) 47 f/s (2 sig figs) Shortcuts: (mph = miles/hour) 1 m/s = 3.6 km/hr 2.237 mph 3.281 ft/s 1 mph 1.467 f/s (1.46666666…) 1.609 km/hr 0.4470 m/s 1 f/s = 0.3048 m/s .6818 mph (.6818181818…) 1.0973 km/hr 1 km/hr 0.2778 m/s 0.6214 mph 0.9113 ft/s W 47 f/s
Convert 88.0 feet/second to mph 5280 ft = 1 mi 3600 s = 1 hr 88 ft( 1 mi )(3600 s) = 60 mph s (5280 ft)( 1 hr ) 60.0 mph Shortcuts: (mph = miles/hour) 1 m/s = 3.6 km/hr 2.237 mph 3.281 ft/s 1 mph 1.467 f/s (1.46666666…) 1.609 km/hr 0.4470 m/s 1 f/s = 0.3048 m/s .6818 mph (.6818181818…) 1.0973 km/hr 1 km/hr 0.2778 m/s 0.6214 mph 0.9113 ft/s W 60.0 mph
Convert 27.2 m/s to km/hr 1000 m = 1 km 3600 s = 1 hr 27.2 m ( 1 km )(3600 s) = 97.92 km/hr s (1000 m)( 1 hr ) 97.9 km/hr Shortcuts: (mph = miles/hour) 1 m/s = 3.6 km/hr 2.237 mph 3.281 ft/s 1 mph 1.467 f/s (1.46666666…) 1.609 km/hr 0.4470 m/s 1 f/s = 0.3048 m/s .6818 mph (.6818181818…) 1.0973 km/hr 1 km/hr 0.2778 m/s 0.6214 mph 0.9113 ft/s W 97.9 km/hr
Convert 110. km/hr to m/s 1000 m = 1 km 3600 s = 1 hr 110 km (1000 m)( 1 hr ) = 30.55556 m/s hr ( 1 km )(3600 s) 30.6 m/s Shortcuts: (mph = miles/hour) 1 m/s = 3.6 km/hr 2.237 mph 3.281 ft/s 1 mph 1.467 f/s (1.46666666…) 1.609 km/hr 0.4470 m/s 1 f/s = 0.3048 m/s .6818 mph (.6818181818…) 1.0973 km/hr 1 km/hr 0.2778 m/s 0.6214 mph 0.9113 ft/s W 30.6 m/s
A car traveling 80. km/hr will go how far (in meters) in 2.7 seconds? 1000 m = 1 km 3600 s = 1 hour (60x60) (km/hr)/(3.6) = m/s 80. km/hr(1000m/km)(3600s/h) = 22.22 m/s v = s/t 22.22 m/s = x/(2.7 s) s = (22.22 m/s)(2.7 s) = 60 m= 60. m Shortcuts: (mph = miles/hour) 1 m/s = 3.6 km/hr 2.237 mph 3.281 ft/s 1 mph 1.467 f/s (1.46666666…) 1.609 km/hr 0.4470 m/s 1 f/s = 0.3048 m/s .6818 mph (.6818181818…) 1.0973 km/hr 1 km/hr 0.2778 m/s 0.6214 mph 0.9113 ft/s W 60. m
A car goes 132 feet in 3.1 seconds. What is its speed in miles per hour? v = s/t v = (132 f)/(3.1 s) = 42.5806 f/s 42.5806 f/s(3600 s/h)/(5280 f/mi) = 29 mph Shortcuts: (mph = miles/hour) 1 m/s = 3.6 km/hr 2.237 mph 3.281 ft/s 1 mph 1.467 f/s (1.46666666…) 1.609 km/hr 0.4470 m/s 1 f/s = 0.3048 m/s .6818 mph (.6818181818…) 1.0973 km/hr 1 km/hr 0.2778 m/s 0.6214 mph 0.9113 ft/s W 170 f
A Baseball going 75 mph takes how much time to go 90. feet? 75 mi/hr(5280 ft/1 mi)(1 hr/3600 s) = 110 f/s v = s/t 110 f/s = (90. f)/t t = (90. f)/(110 f/s) = .818181818 s = .82 s Shortcuts: (mph = miles/hour) 1 m/s = 3.6 km/hr 2.237 mph 3.281 ft/s 1 mph 1.467 f/s (1.46666666…) 1.609 km/hr 0.4470 m/s 1 f/s = 0.3048 m/s .6818 mph (.6818181818…) 1.0973 km/hr 1 km/hr 0.2778 m/s 0.6214 mph 0.9113 ft/s W .82 s