You place an ice cube of mass 7.50×10−3kg and temperature 0.00∘C on top of a copper cube of mass 0.540 kg. All of the ice melts, and the final equilibrium temperature of the two substances is 0.00∘C. What was the initial temperature of the copper cube? Assume no heat is exchanged with the surroundings.

The value is

Explanation:

From the question we are told that

The mass of the ice cube is

The temperature of the ice cube is

The mass of the copper cube is

The final temperature of both substance is

Generally form the law of thermal energy conservation,

The heat lost by the copper cube = heat gained by the ice cube

Generally the heat lost by the copper cube is mathematically represented as

The specific heat of copper is

Generally the heat gained by the ice cube is mathematically represented as

Here L is the latent heat of fusion of the ice with value

So

=>

So

=>    

5 w for 1hr = 5x60x60 joules=300x60=3000x6=18,000j as total energy conversion. efficiency of bulb needed for radiant to thermal within 18000