Consider two identical rooms: one with a 2-kW electric resistance heater and the other with two couples fast dancing. Will the room with the couples fast dancing heat up faster than the room with 2-kW electric resistance heater? An average fast-dancing person dissipates 600 Cal/h of energy (sensible and latent).

No, the room with the dancing couple will heat up slower than the room with 3-KW electric resistance heater.

Explanation:

An average person dissipates 600 Cal/h of energy.

Converting this to J/s (Watt)

Power dissipated by an average person fast dancing = (600 Cal/h) (4.184 J/1Cal) (1 h/3600 s)

Power dissipated by an average person fast dancing = 0.7 W

Since, two persons are fast dancing in 2nd room. Therefore,

Power dissipated in 2nd room = P2 = 0.7 W x 2

Power dissipated in 2nd room = 1.4 W

While, the power dissipation in 1st room due to heater is:

P1 = 2 KW = 2000 W

Since, P1 > P2

Therefore, the room with the fast dancing couple will heat up slower than the room with heater.