# physics

A cup of tea has a mass of 140 grams. Its temperature starts out at T = 40 C. It sits for a while and cools off to room temperature T= 22 C. Answer the next 3 questions about the cup of tea.

1. What is the overall temperature change for the cup of tea?

a. 40 C
b. 22 C
c. 18 C
d. -18 C ****
e. -22 C

2. Is this event consistent with the Law of Conservation of Energy?

a. No. The heat leaves the tea, but this doesn't warm up the room.
b. No. The heat leaves the tea and warms up the room, but doesn't warm up the room enough to measure.
c. Yes. The heat leaves the tea, and the room warms up as much as the tea cools down.
d. Yes. The heat leaves the tea and warms up the room, but doesn't warm up the room enough to measure. *****

Solve for the amount of heat energy in kJ lost by the tea. Recall the specific heat of water is 4.18 joules per gram per degree Celsius. [ 4.18 J/(g C) ]. Report your answer using only 1 digit after the decimal with NO UNITS. (Be sure you calculate your answer in kilojoules (kJ)). *

1. 👍 0
2. 👎 0
3. 👁 38
1. trick is kJ instead of J
use 4.18 *10^-3 kJ /(g C)
heat lost = 4.18*10^-3 kJ/( g C) * 140 g * 18 C = 10.5

1. 👍 1
2. 👎 0
2. .... and you did the rest right

1. 👍 1
2. 👎 0

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