(a) Which one of the following represents the greatest speed? 1m/s, 1 km/h, 1 ft/s, or mi/h.?

Question

(b) Express the speed 15.0 m/s in mi/h. thank you

Answer 1

(a)

get them all in the same units....

1 m/s = 1 m/s x (1km/1000m)x(3600s / hr) = 3.6 km/hr

1 ft/s = 1 ft/s x (12 in/1 ft) x (2.54 cm/in)x(1 m / 100 cm) x 1km/1000m)x(3600s / hr) ≈1.1 km/hr

1 mi/hr = 1 mi/hr x (5280 ft / mi) x (12 in/1 ft) x (2.54 cm/in)x(1 m / 100 cm) x (1 km/1000 m) = 1.6 km/hr

so, 1 m/s > 1 mi/hr > 1 ft/s > 1 km/hr

(b)

15 m/s = 15 m/s x (100 cm / 1 m ) x (1 in / 2.54 cm) x ( 1 ft / 12 in) x (1 mi / 5280 ft) x ( 3600 s / hr) = 33.6 mi/hr

Answer 2

a) Well, let's try to convert the units, and see what we get.
1 km = 1000 m
1 m = 3.28 ft
1 mi = 5280 ft
1 h = 3600 s

so - 1 km/h = 1000m/3600s = 1/3.6 m/s = 0.278 m/s
1 ft/s = 1/3.28 m/s = 0.305 m/s
1 mi/h = 5280 ft/3600s = (5280/3.28)m/3600s = 0.447 m/s

1m/s represents the fastest speed.

b) 15.0 m/s * (1 mi/h)/(0.447 m/s) = 15.0/0.447 mi/h = 33.6 mi/h

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Beat me to it. Well, that's two different ways to go about it, and you know it's correct, as both ways agree.