<span>1.) It is 6.00km from your home to the physics lab. As part of your physical fitness program, you could run that distance at 10.0km/hr (which uses up energy at the rate of 700W ), or you could walk it leisurely at 3.00km/hr (which uses energy at 290 W).
A.)Which choice would burn up more energy?
running or walking?
b.)How much energy (in joules) would it burn?
c.)Why is it that the more intense exercise actually burns up less energy than the less intense one?
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Answers
billrussell42
Best Answer: running, at 10 km/hour for 6 km is
6 km / 10 km/hour = 0.6 hour or 36 min
energy used is 700 watts or 700 joules/s x 36 min x 60s/min = 1.512e6 joules or 1.5 MJ
walking, at 3 km/hour for 6 km
6 km / 3 km/hour = 2 hour or 120 min
energy used is 290 watts or 290 joules/s x 120 min x 60s/min = 1.872e6 joules or 1.8 MJ
C) should be obvious
PS, this has nothing to do with potential energy.
billrussell42 · 5 years ago
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Simon van Dijk
I assume the watt consumption is per hour. Then running 6km at 10.0 km/h results in 700*6/10 = 420 w.h and walking in 290*6/3 = 580 w.h So walking would burn up more energy (kwh)
b) 1 kilowatt hour = 3 600 000 joules
so 420 wh = 0.42 kwh = 1.51.10^6 joule
c) when you put more effort in making the distance your energy is used more efficient.
Simon van Dijk · 5 years ago
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P = 43 * 10^3
V = 12 L
P' =?
V' = 8 L
PV = P'V'
43*10^3* 12 = P' * 8
I know you can do it from here, mate ;)
Here we can use momentum conservation as there is no external force on sled and child while he jump on sled
by momentum conservation equation
since sled and child both moves with same speed so here they both will have same final speed "v"
by solving above equation we will have
25 v = 80
v = 3.2 m/s
So they will move together with speed 3.2 m/s
Answer:
Heat lost thru doors & windows = (100 - 75 - 5) = 20
20% is the fraction of heat lost thru doors and windows
One wants to obtain the largest savings per unit of cost
roof:
200 / 600 = 1/3
150 / 1000 = .15
40 / 2300 = .017
The largest of these is 1/3 so the most benefit would be obtained by insulating the roof
Since heat loss thru the roof depends on heat loss thru the attic, this is the most cost effective in reducing heat loss
The more the difference in temperature between the ceiling and roof (attic) the more heat will be lost thru the roof, so insulating the roof will decrease the heat loss of the attic
