Part A A typical student listening attentively to a physics lecture has a heat o

Question

Part A

A typical student listening attentively to a physics lecture has a heat output of 120 W . How much heat energy does a class of 80 physics students release into a lecture hall over the course of a 50 min lecture?

Express your answer using two significant figures.

Part B

Assume that all the heat energy in part (a) is transferred to the 3600 m3 of air in the room. The air has specific heat capacity 1020 J/(kgK) and density 1.20 kg/m3. If none of the heat escapes and the air conditioning system is off, how much will the temperature of the air in the room rise during the 50 min lecture?

Express your answer using two significant figures.

Part C

If the class is taking an exam, the heat output per student rises to 260 W . What is the temperature rise during 50 min in this case?

Express your answer using two significant figures.

Explanation / Answer

Here ,

Power , P = 120 W

number , N = 80

time , t = 50 min

heat energy released = Power * time * N

heat energy released = 120 * 80 * 50 * 60

heat energy released = 2.9 *10^7 J

the heat energy released during the lecture is 2.9 *10^7 J

b)

mass of air , m = volume * density

m = 3600 * 1.20 Kg

let the rise in temperature is del T

haet energy = mass * del T * S

2.9 *10^7 = 1020 * 3600 * 1.20 * del T

del T = 6.54 degree C

the temperature of air will raise by 6.54 degree C

part c)

for the Power = 260 W

haet energy = mass * del T * S

80 * 50 * 60 *260 = 1020 * 3600 * 1.20 * del T

del T = 14.2 degree

the temperature of the room will rise by 14.2 degree

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