Physics Chapter 15
Water is most dense at ___________.
4°C
Compared to a giant iceberg, a hot cup of coffee has
higher temperature, but less internal energy.
If you stake out a plot of land with a steep tape on a vary hot day, the actual amount of land you will have will be
smaller than measured
Heat energy travels from an object with high
temperature to an object with a lower temperature.
The fact that the thermometer "takes its own temperature" illustrates
thermal equilibrium
The fact that a thermometer "takes its own temperature" illustrates
thermal equilibrium.
Why does all the water in a lake have to be cooled to 4°C before the surface water can be cooled below 4°C?
When water is cooled to 4°C, it sinks and deeper, warmer, water rises to the surface.
Pour a liter of water at 40 degrees C into a liter of water at 20 degrees C and the final temperature of the two becomes
at or about 30 degrees C
Heat energy is measured in units of
joules or calories
Place a kilogram block of iron at 40 degrees C into a kilogram of water at 20 degrees C and the final temperature of the two becomes
less than 30 degrees C
The quantity of heat that a substance can transfer relates to its
mass change in its temperature specific heat capacity
If the specific heat of water were lower than it is, ponds in the cold of winter would be
more likely to freeze.
Tomatoes have a higher specific heat capacity than dough. This means that when you bite into a hot pizza
the tomato sauce feels hotter than the dough
During a very cold winter, water pipes sometimes burst. The reason for this is
water expands when freezing.
What is meant when we say that a thermometer is in thermal equilibrium with another object?
Heat no longer flows between the object and thermometer when both are at the same temperature.
Northeastern Canada and much of Europe receive about the same amount of sunlight per unit area. Why, then, is Europe generally warmer in the winter?
The gulf stream carries warm, high heat capacity water past the west coast of Europe.
Which of the following changes would make the water balloon more likely to pop? (Ignore effects of convection within the fluid.)
Use a thicker balloon. Use a liquid that has a lower heat capacity than water.
The amount of heat needed to raise the temperature of 1 g of water by 1°C is ___________.
1 calorie
Before ice can form on a lake, all the water in the lake must be cooled to
4 degrees C.
Does a substance that heats up quickly have a high or a low specific heat capacity?
A low specific heat capacity
Select the correct equations that show that 2600 cal are required to raise the temperature of 260 g of water from 22∘C to 32∘C. For the specific heat capacity c, use 1 cal/(g⋅∘C).
Q=cmΔT=(1cal/(g⋅∘C))(260g)(32∘C−22∘C)=2600cal
What are the temperatures for freezing water on the Celsius and Fahrenheit scales? For boiling water?
Freezing: 0°C, 32°F; boiling: 100°C, 212°F
In which direction does heat flow spontaneously between hot and cold objects?
From high temperature to low temperature
The fact that desert sand is very hot in the day and very cold at night is evidence that sand has
a low specific heat
Which of the following normally warms up fastest when heat is applied?
a) water b) iron* c) glass d) wood e) all of the above
Aluminum has a specific heat capacity more than twice that of copper. Place equal masses of aluminum and copper wire in a flame and the one to undergo the fastest increase in temperature will be
copper
When a bimetallic bar made of copper and iron strips is heated, the bar bends toward the iron strip. The reason for this is
copper expands more than iron
When water at 4 degrees C is heated it expands. When water at 4 degrees C is cooled it
expands.
When most substances are heated, molecules inside move faster and take up more space, resulting in thermal
expansion.
When you touch a cold piece of ice with your finger, energy flows
from your finger to the ice.
The moderate temperature of islands throughout the world as much to do with water's
high specific heat
When an iron ring is heated, the hole becomes
larger.
Place a 1-kilogram block of iron at 40°C into 1 kilogram of water at 20°C and the final temperature of the two after the thermal equilibrium is established becomes
less than 30°C.
As in the video, the mass of the metal is the same as that of the water. Room temperature is about 20∘C before the start of the experiment. The water heats up to 40∘C, and the mystery metal heats up to 80∘C. Compared to that of water, the heat capacity of our mystery metal is
one-third as great.
The white hot sparks that strike your skin from the 4th of July type sparklers don't harm you because
the energy per molecule is high, but little energy is transferred because of the few molecules in the spark.
In terms of thermal expansion it is important that
the fillings in your teeth expand at the same rate as teeth.
