Problem I Marcella (see warmup problem, above) gets her car moving steadily at 4m/s but suddenly someone stops ahead to assist h
1 answer:
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Answer:
1353.38 Watt
Explanation:
T₁ = Initial temperature of the house = 35°C
T₂ = Final temperature of the house = 20°C
Δt = Time taken to cool the house = 38 min = 38×60 = 2280 s
m = mass of air in the house = 800 kg
Cv = Specific heat at constant volume = 0.72 kJ/kgK
Cp = Specific heat at constant pressure = 1.0 kJ/kgK
Heat removed
q = mCvΔT
⇒q = 800×720×(35-20)
⇒q = 8640000 J
Average rate of hear removal
∴ Power drawn by the air conditioner is 1353.38 Watt
According to the Work-Energy Theorem, the work done on an object is equal to the change in the kinetic energy of the object:
Since the car ends with a kinetic energy of 0J (because it stops), then the work needed to stop the car is equal to the initial kinetic energy of the car:
Replace m=1100kg and v=112km/h. Write the speed in m/s. Remember that 1m/s = 3.6km/h:
Therefore, the answer is: 532,346 J.