Water can be heated in tightly woven baskets by dropping in hot rocks. The technique is useful for cooking in the absence of metal or pottery vessels. Estimate the size (in liters) of basket needed to hold the rocks and water if 5 L of boiling-hot (100°C) water is required. The water comes from a well at 10°C, and the rocks (granite with a density of 2.7 g cm−3) come from a hot fire at 900°C. Take data from Table 10−1. List the assumptions required to make the estimate.

Question

A)6 L
Assumptions:
(1) the density of the water does not change between 10.0°C to 100°C
(2) the density of the rock is 2.7 g cm−3 at 100°C
(3) the specific heat capacities of the water and rock do not change with temperature
(4) no heat is lost to the surroundings through the walls of the basket
(5) no heat is used to warm up the walls of the basket

B)8 L
Assumptions:
(1) the density of the water does not change between 10.0°C to 100°C
(2) the density of the rock is 2.7 g cm−3 at 100°C
(3) the energy created by the rocks are transfered to the water at a constant rate.
(4) heat is lost to the surroundings through the walls of the basket
(5) The rocks decrease in size as a function of temperature

C)6 L
Assumptions:
(1) the density of the water does not change between 10.0°C to 100°C
(2) the density of the rock is 2.7 g cm−3 at 100°C
(3) the energy created by the rocks are transfered to the water at a constant rate.
(4) heat is lost to the surroundings through the walls of the basket
(5) The rocks decrease in size as a function of temperature

D)8 L
Assumptions:
(1) the density of the water does not change between 10.0°C to 100°C
(2) the density of the rock is 2.7 g cm−3 at 100°C
(3) the specific heat capacities of the water and rock do not change with temperature
(4) no heat is lost to the surroundings through the walls of the basket
(5) no heat is used to warm up the walls of the basket

E)8 L
Assumptions:
(1) the density of the water does not change between 10.0°C to 100°C
(2) the density of the rock is 2.7 g cm−3 at 100°C
(3) the specific heat capacities of the water and rock do not change with temperature
(4) heat is lost to the surroundings through the walls of the basket
(5) The rocks decrease in size as a function of temperature