Write these down while you wait: 1 hr = 60 min = 3600 sec 1 km = 1000 m .6214 mile

Write these down while you wait:1 hr = 60 min = 3600 sec1 km = 1000 m .6214 mile1 mile = 5280 ft = 1760 yards 1609 m1 m 3.281 ft1 yard = 3 feetShortcuts: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 sec1 km = 1000 m .6214 mile1 mile = 5280 ft = 1760 yards 1609 m1 m 3.281 ft1 yard = 3 feetShortcuts: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 Analysis Contents:• Handy things to know• Ways to convert• Whiteboard practice

Ways to convert units:

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1. Unit cancellation2. Calculator’s built in (TI 85/86)3. Conversion factors4. Google

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)

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?)

Calculator (TI 85/86)2nd CONV, MORE, MORE, SPEED, 30 mi/hr > ft/s

Whiteboards: Conversions1 | 2 | 3 | 4 | 5

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Convert 32 mile/hour to feet/second5280 ft = 1 mi3600 s = 1 hr

32 mi(5280 ft)( 1 hr ) = 46.933333 hr ( 1 mi )(3600 s)47 f/s (2 sig figs)

47 f/s W

Shortcuts: (mph = miles/hour)1 m/s = 3.6 km/hr 2.237 mph 3.281 ft/s1 mph 1.467 f/s (1.46666666…) 1.609 km/hr 0.4470 m/s1 f/s = 0.3048 m/s .6818 mph (.6818181818…) 1.0973 km/hr1 km/hr 0.2778 m/s 0.6214 mph 0.9113 ft/s

Convert 88.0 feet/second to mph5280 ft = 1 mi3600 s = 1 hr

88 ft( 1 mi )(3600 s) = 60 mph s (5280 ft)( 1 hr )60.0 mph

60.0 mph W


Convert 27.2 m/s to km/hr1000 m = 1 km3600 s = 1 hr

27.2 m ( 1 km )(3600 s) = 97.92 km/hr s (1000 m)( 1 hr )97.9 km/hr

97.9 km/hr W


Convert 110. km/hr to m/s1000 m = 1 km3600 s = 1 hr

110 km (1000 m)( 1 hr ) = 30.55556 m/s hr ( 1 km )(3600 s)30.6 m/s

30.6 m/s W


A Baseball going 75 mph takes how much time to go 90. feet?(hint convert mph to ft/s first)

75 mi/hr(5280 ft/1 mi)(1 hr/3600 s) = 110 f/sv = s/t110 f/s = (90. f)/tt = (90. f)/(110 f/s) = .818181818 s = .82 s

.82 s W


A car traveling 80. km/hr will go how far (in meters) in 2.7 seconds?(hint convert km/hr to m/s first)

80. km/hr(1000m/km)(3600s/h) = 22.22 m/s v = s/t22.22 m/s = x/(2.7 s)

s = (22.22 m/s)(2.7 s) = 60 m= 60. m

60. m W


A car goes 132 feet in 3.1 seconds. What is its speed in miles per hour?(find the answer, and convert to mph)

v = s/tv = (132 f)/(3.1 s) = 42.5806 f/s42.5806 f/s(3600 s/h)/(5280 f/mi) = 29 mph

170 f W


Write these down while you wait: 1 hr = 60 min = 3600 sec 1 km = 1000 m .6214 mile

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