PHYSICS FINAL EXAM CH 11-17 Flashcards
(21 cards)
When an iron ring is heated, does the hole get bigger or smaller?
The hole gets bigger. It is easier to expand outwards, which is less constricting
Does a completely submerged object always displace its own weight, volume, or mass?
The submerged object always displaces its own volume
You have submerged 5 N block of different densities. Which will have the greatest buoyant force
The greatest buoyant force will be on the block with the least density. This is because it is less
compact, and will take up more space, thus displacing more fluid when submerged.
Where does ice form first - at the surface or bottom of bodies of water? Think about all the fish!
Ice forms at the surface first. Below 4° Celsius, water becomes less dense as it gets colder, causing
water about to freeze to float to the top
Two objects of the same size are submerged in water. What can you say about the buoyant force on each?
Since they are the same objects (same density), and the same size (volume), they would displace the
same amount of fluid. The buoyant force will then be the same for both
What happens to the freezing point of water when salt is added to it
The freezing point decreases, so water can stay in liquid state at 0o Celsius
Give examples or applications of Archimedes’ principle, Pascal’s principle, and Bernoulli’s principle
- Archimedes’ Principle: Any object fully or partially submerged in a fluid will be acted upon by a
buoyant force equal to the weight of the displaced fluid. Example: The air around you exerts a buoyant
force on you as you sit in a chair. - Pascal’s Principle: In a fluid at rest in a closed container, a pressure change in one part is transmitted
without loss to every portion of the fluid and the walls of the container. Example: When you apply a
Heimlich maneuver, your pressure is applied to everything inside your body, dislodging any stuck
object
How much heat is needed to change the temperature of 5 g water (c =1 cal/goC) by 6
degrees Celsius?
Q = m c T= 5 g (1 cal/goC) (6oC) = 30 cal
If 500 calories were added to a 5 g substance (c = 50 cal/goC), what is the resulting
temperature change?
T = Q/m c = 500 cal /[(5 g) (50 cal/goC)] = 2oC
What does it mean when a substance has a high specific heat?
A high specific heat means that the substance requires a higher amount of heat to produce the same
temperature change as a substance that has a lower specific heat
What happens to boiling water when heat is added to it? What about ice at 0oC
When heat is added to boiling water, the temperature stays the same until all the water has turned to
steam. For ice at 0oC, continuous application of heat will result in a phase change, and the temperature
will only go up after all the ice has melted
When will balloons stop rising in air?
Balloons will stop rising in the air when their density equals that of the surrounding air
What can you say about the motion of individual particles at a given temperature?
At any given temperature, the individual particles are moving with a great variety of speeds
What determines the size of atoms?
The size of atoms are determined by the electrical force of attraction between the electron and the
nucleus, as well as the repulsion between the energy levels
If different liquids were used to make barometers, which would have the highest column and why
- The one with the highest column is the one with the least density.
- Pressure = (density)(gravitational acceleration)(height)
What determines buoyant force?
Since buoyant force is the weight of the displaced fluid, it depends on the mass which is also the
product of the density and the volume
When an object sinks, what can you say about the buoyant force on it compared to its weight?
For an object that sinks, the object’s weight is greater than the buoyant force on it
What is the direction of heat flow?
Heat will naturally flow from hot to cold objects
Describe what happens to the temperature and phase of water as heat is added to it
When heat is added to a substance, there will either be a temperature change or a phase change, but
not at the same time
For two objects exchanging heat, is the temperature change for both objects the same? (think about dropping 1
g vs dropping 500 g of red-hot metal into a glass of water
The amount of heat exchanged will be the same, but the temperature changes are not necessarily the
same. A metal dropped in a huge container of water can undergo a huge temperature change while the
water barely changes temperature
What does it mean when a substance has a high specific heat? Low specific heat?
High specific heat means a greater heat requirement to produce a temperature change
