Asked by TOM

It is 5.0 km from your home to the Physics lab and your car is out of gas. You could run that distance
at 10 km/h, which uses up energy at the rate of 700 W; or you could walk it leisurely at 3.0 km/h,
which uses energy at 300 W.
(a) Calculate how much energy both choices would burn up.
(b) The conversion between energy units is: 1 Cal (food calaorie) = 1 kcal (kilocalorie) = 1000 cal
(thermochemical calorie) = 4184 J (joules). Calculate how much energy both choices would burn
up in units of J, cal and Cal.
(c) Which choice would burn up more energy?
Answered by TOM
Can someone help me figure out what formula to use!!
Answered by Damon
10 km/hr = 10/3.6 = 2.78 m/s
3 km/hr = 3/3.6 = .833 m/s

5 km at 10 km/hr --> 30 min which is 30 *60 = 1800 s
energy = 700*1800 = 1.26*10^6 Joules

5 km at 3 km/hr --> 6,000 s

6,000 s * 300 w = 1.8*10^6 Joules

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