B.1 - 5 - Using power in heat equations

What is the correct relationship between power (P), heat (Q), and time (t)?

• P = Q * t

• P = Q / t

• P = t / Q

• P = Q + t

A 10 kg block of ice at its melting point is completely melted by a 5000 W power supply. Given the latent heat of fusion for water is 3.3 x 10^5 J/kg, how long does it take to melt the ice?

• 330 seconds

• 660 seconds

• 1320 seconds

• 1650 seconds

What power is required to heat 20 kg of water from 10°C to 30°C in 5 minutes? The specific heat of water is 4.2 x 10^3 J/kg°C.

• 2800 W

• 4200 W

• 5600 W

• 8400 W

A stove provides 2000 W to 10 kg of water initially at 20°C. How much time would it take to completely evaporate the water? (Specific heat of water = 4.2 x 10^3 J/kg°C, Latent heat of vaporization = 2.3 x 10^6 J/kg, Boiling point = 100°C)

• 1680 seconds

• 11500 seconds

• 13180 seconds

• 14800 seconds