100 W heater is used to melt 50 g of ice at OC. How long should the heater be switched on? (Specific latent heat of fusion of ice is 334 J/g)
Correct answer: C. 2.8 min
- A. 28 min
- B. 16.7 min
- C. 2.8 min
- D. 167 min
Explanation
To melt 50 g of ice at 0°C, we need to supply energy equal to:Q = m × Lf where Q is the heat energy, m is the mass of ice, and Lf is the specific latent heat of the fusion of ice. Substituting the given values, we get: Q = 50 g × 334 J/g Q = 16700 J Now, the power of the heater is given as 100 W, which means that it can supply 100 J of energy every second. Therefore, the time required to supply 16700 J of energy is: t = Q/P t = 16700 J / 100 W t = 167 seconds t= 2.8 min Mathematically other options are incorrect
Last updated
About Thermal Equilibrium and Heat
Thermal equilibrium means that bodies in contact have the same temperature and no net heat flows between them. The topic distinguishes heat from temperature, uses the zeroth law of thermodynamics, and covers heat transfer, specific heat capacity, thermal expansion and the conditions for reaching equilibrium.
Practise Thermodynamics
714 free Thermodynamics MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Exams that ask Physics questions like this
Physics is on 13 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
Related questions
100 W heater is switched on for 5 minutes to melt ice. What is the mass of ice that melts at 0oC? ( The specific latent heat of fusion of ice is 334 J/g).
100 W heater is used for 5 minutes to heat 500 g of water. What is the change in the temperature of the water? (The specific heat capacity of water is 4.2 J/gC).
100 W heater is used to melt 50 g of ice at 0°C. How long should the heater be switched on? (Specific latent heat of fusion of ice is 334 J/g)
100W heater is used for 5 minutes to heat 500g of water. What is the change in the temperature of water? (Specific heat capacity of water is 4.2 J/gC)
100W heater is used for 5 minutes to heat 500g of water. What is the change in temperature of water? (Specific heat capacity of water is 4.2 J/gC)