Metal weights with a total weight of 1 kg heated in boiling water are lowered into water weighing 300 g

Metal weights with a total weight of 1 kg heated in boiling water are lowered into water weighing 300 g, the temperature of which is 10 degrees. The water temperature rises by 21 degrees. What materials can weights be made of?

mw = 300 g = 0.3 kg.

tv = 10 ° C.

Cw = 4200 J / kg * ° С.

mg = 1 kg.

Δt = 21 ° C.

Cg -?

Since the weight was in boiling water, its initial temperature is tg = 100 ° C.

When the weight is lowered into the water, after the establishment of thermal equilibrium, the temperature of the weight will become the same as the water temperature t: t = tv + Δt.

Qg = Cr * mg * (tg – t) = Cr * mg * (tg – tv – Δt).

Qw = Sv * mw * Δt.

Cr * mg * (tg – tv – Δt) = Сw * mw * Δt.

Cr = Sv * mw * Δt / mg * (tg – tv – Δt).

Сg = 4200 J / kg * ° С * 0.3 kg * 21 ° С / 1 kg * (100 ° С – 10 ° С – 21 ° С) = 383.5 J / kg * ° С.

According to the table of specific heat capacity of substances, it can be copper, zinc, brass.

Answer: weights can be made of copper, zinc, brass.