Intro to Physics – Homework #3 Concepts Review

A comprehensive set of Q&A flashcards reviewing pressure, fluids, buoyancy, gas laws, temperature, heat, and thermal expansion concepts from Homework #3.

What two quantities are multiplied/divided to define pressure (P)?

Force and area (P = F / A).

For two identical books, one flat and one standing, which property remains unchanged?

Their weight remains the same.

Why can Sara lie safely on a bed of sharp nails?

Her weight is distributed over hundreds of nails, greatly reducing pressure on any single point.

When you are standing upright, where is your blood pressure highest?

In your feet.

Why is a dam built thicker at the bottom than at the top?

Because water pressure increases with depth.

On what two factors does the pressure at a point in a liquid depend?

Liquid depth and liquid density.

From which hole in a water tower wall does water spurt out fastest?

The hole closest to the bottom, where pressure is greatest.

A completely submerged object always displaces what amount of fluid?

A volume of fluid equal to its own volume.

If a 10-ton ship floats, what is the buoyant force acting on it?

10 tons (equal to the ship’s weight).

For two submerged 1-cm³ blocks (aluminum and lead), which experiences the greater buoyant force?

Both experience the same buoyant force because they displace the same volume of water.

How does a fish’s density compare with the density of water?

Approximately the same (allowing neutral buoyancy).

Because lobsters live on the ocean floor, how does their density compare with seawater?

It is greater than the density of seawater.

A lobster on a scale at the ocean floor weighs compared with the same lobster weighed in air.

Less, due to the buoyant force of seawater.

How does a life jacket keep you afloat?

It lowers the combined density of you and the jacket below that of water.

Which physical principle is demonstrated by hydraulic lifts and presses?

Pascal’s principle.

In a hydraulic press, what quantity can never exceed the input value?

Energy output can never exceed energy input.

Does the air in a classroom have mass, weight, and energy?

Yes—air possesses all three.

What happens to marshmallows placed in a vacuum chamber?

They expand and become larger.

If a gas is compressed to half its original volume at constant temperature, what happens to its pressure?

The pressure doubles (Boyle’s Law).

Archimedes’ principle applies to which states of matter?

All fluids—both liquids and gases.

The buoyant force of air on an object equals the displaced by the object.

Weight of the air displaced.

Which objects experience a buoyant force in air?

All objects, including gas-filled balloons and people.

How does the pressure inside an inflated, stretched balloon compare with outside air pressure?

It is greater inside the balloon.

Why can an umbrella lift upward on a windy day?

Wind reduces air pressure over the curved top surface (Bernoulli effect).

Which type of molecular motion is most directly related to temperature?

Translational kinetic motion of molecules.

Temperature is most closely tied to the average molecular energy.

Kinetic energy.

Which two temperature scales use equal-sized degrees?

Celsius and Kelvin.

Which common temperature scale has the smallest degree interval?

Fahrenheit.

How much energy raises 1 gram of water by 1 °C?

4.19 joules (1 calorie).

When a ‘C’-shaped metal ring is heated, what happens to the width of its gap?

The gap widens.

A thermometer "takes its own temperature" because of what thermal principle?

Thermal equilibrium (Zeroth Law of Thermodynamics).

Which is hotter: boiling tea in a cup or in a large pail?

Both are at the same temperature (100 °C at standard pressure).

Cooling 10 g of water by 1 °C releases how much heat?

41.9 joules.

Heat energy naturally flows from an object of higher to one of lower .

Temperature; temperature.

Mixing 1 L of 40 °C water with 1 L of 20 °C water yields a final temperature of about .

30 °C.

When an iron ring is heated, does the hole inside get larger or smaller?

Larger—everything expands uniformly, including the hole.

The heat transferred by a substance depends on its mass, temperature change, and .

Specific heat capacity.

Water is densest at 4 °C. To make 4 °C water expand, should you raise or lower its temperature slightly?

Either raising or lowering the temperature causes expansion.

Water pipes burst in freezing weather mainly because

Water expands when it freezes.

Equal masses of aluminum and copper wire are placed in a flame. Which heats up faster?

Copper, because it has a lower specific heat capacity.

Island climates are moderate largely because of water’s .

High specific heat capacity.

When you touch ice, in which direction does energy (heat) flow?

From your finger to the ice.

Heating a sealed can of air increases the air’s .

Temperature (mass remains constant).

Between 0 °C and 4 °C, warming water slightly makes it .

Contract until it reaches maximum density at 4 °C.

For equal temperature changes, which state of matter generally expands the most?

Gases.

As a metal plate with a hole cools, the diameter of the hole .

Decreases (contracts).

The deep bottom water of Lake Tahoe always remains at approximately .

4 °C (temperature of maximum-density water).

A heated bimetallic strip bends toward its iron side because

Copper expands more than iron.

Which is larger: one Kelvin or one Celsius degree?

They are the same size.

What is the lowest possible temperature in nature?

−273 °C (0 K, absolute zero).