An electric clothes dryer draws 20 A at 220 V.If the clothes put into the dryer have a mass of 7.0 kg when wet and 3.0 kg dry,how long does it take to dry the clothes? (Assume all heat energy goes into vaporizing water,L_v = 2.26 × 10⁶ J/kg. )

Question

Quizplus · Accepted Answer

The power consumed by the dryer can be calculated using the formula:

Power = Voltage x Current

Power = 220 V x 20 A

Power = 4400 W

We can calculate the total heat energy required to vaporize the water from wet clothes using the formula:

Q = m x LS

Where, 
Q = Heat Energy Required (Joules) 
m = Mass of water to be vaporized (kg) 
LS = Latent Heat of Vaporization of Water (J/kg)

Here, the mass of water to be vaporized can be calculated as:

m = (mass of wet clothes) - (mass of dry clothes)

m = 7.0 kg - 3.0 kg

m = 4.0 kg

Substituting the values, we get:

Q = 4.0 kg x 2.26 x 10^6 J/kg

Q = 9.04 x 10^6 J

The time required to vaporize the water can be calculated using the formula:

Time = Q / Power

Time = 9.04 x 10^6 J / 4400 W

Time = 2054.55 seconds

Time = 34.2 minutes

Therefore, the drying time for the clothes is approximately 34 minutes, which is closest to option D (34 min).

An Electric Clothes Dryer Draws 20 a at 220 V