In: Physics
Hector read that the traditional drink in Tibet is tea with
added butter. Inspired by this idea, he decides to investigate how
a thin layer of fat on the top of a hot liquid affects the cooling
of the liquid. He performs two different experiments.
Experiment 1: Hector pours 100 ml of boiling water into
each of two Styrofoam cups and adds a thin (2.0-mm) layer of hot
oil (at about 100∘C ) to one of the cups. He measures the initial
temperature in the cups, waits for 10 minutes, and then measures
the temperature again. His measurements are shown below.
Cup A (no oil) |
Cup B (with layer of oil) |
|
Ti | 98∘C | 98∘C |
Tf | 84∘C | 95∘C |
Experiment 2: Hector puts two empty Styrofoam cups on
separate precision scales and zeroes the scales. Then he pours 100
ml of boiling water into each cup and adds a 2.0-mm layer of hot
oil to one of the cups. He records the initial readings of the
scales, waits for 10 minutes, and then records the readings of the
scales again. His data are shown below.
Cup A (no oil) |
Cup B (with layer of oil) |
|
mi | 99.00 g | 104.00 g |
mf | 97.00 g | 104.00 g |
The surface area of the water in the cups is 3.0×10−3m2.
Part F
What other quantities relevant to the investigation can be determined or estimated from Hector's data?
a) The density of water
b) The number of moles of water
c) The rate of evaporation of oil
d) The density of oil