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?
2 answers
Can someone help me figure out what formula to use!!
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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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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