An aluminum calorimeter weighing 50 g is filled with 120 g of water and a 2-ohm spiral connected to a 15 V

| August 13, 2021 | education

An aluminum calorimeter weighing 50 g is filled with 120 g of water and a 2-ohm spiral connected to a 15 V source is lowered. How long does it take for a calorimeter with water to heat up by 9 ° C, if energy losses to the environment can be neglected?

Data: m1 (mass of the calorimeter) = 50 g (0.05 kg); m2 (mass of water in the calorimeter) = 120 g (0.12 kg); R (coil resistance) = 2 ohms; U (voltage) = 15 V; Δt (change in water temperature, calorimeter) = 9 ºС.

Constants: Ca (specific heat capacity of aluminum) = 920 J / (kg * ºС); Sv (specific heat capacity of water) = 4200 J / (kg * ºС).

The operating time of the spiral is determined from the equality: (Ca * m1 + Cw * m2) * Δt = U ^ 2 * t / R; t = (Ca * m1 + Cw * m2) * Δt * R / U ^ 2.

Calculation: t = (920 * 0.05 + 4200 * 0.12) * 9 * 2/15 ^ 2 = 44 s.



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