Physics 102: Fluid And Thermal Physics Exercises

Phy 102 Fluid And Thermal Physics Exercisescomplete The Following Ex

Complete the following exercises related to fluid and thermal physics. Address topics including density, pressure, buoyant force, water flow dynamics, atmospheric pressure effects, thermal properties of materials, heat transfer mechanisms, and properties related to temperature and heat capacity. Provide thorough explanations grounded in physics principles for each question, utilizing appropriate terminology and supporting references.

Paper For Above instruction

Fluid and thermal physics encompass several fundamental principles critical to understanding natural phenomena and engineering applications. This paper systematically addresses the provided exercises, elucidating concepts such as density ranking, pressure calculations, buoyancy, flow velocity variations, atmospheric forces, thermal properties, heat transfer mechanisms, and the behavior of materials under thermal influence. Each question is examined with rigorous scientific reasoning supported by credible sources, highlighting the relevance of these principles in real-world contexts.

Density and Pressure in Fluids

Question 1 involves ranking objects by increasing density, which is defined as mass divided by volume (ρ = m/V). Calculating the density of each object:

• A. 100 g, volume 25 cm³: ρ = 100/25 = 4 g/cm³
• B. 200 g, volume 100 cm³: ρ = 200/100 = 2 g/cm³
• C. 100 g, volume 100 cm³: ρ = 100/100= 1 g/cm³
• D. 400 g, volume 50 cm³: ρ= 400/50= 8 g/cm³

Thus, the ranking from lowest to highest density is: C, B, A, D.

Question 2 explores pressure exerted by objects on surfaces, calculated by P = F/A, where F = mg and A is area:

• A. 10 kg, area 10 cm x 10 cm = 100 cm² = 0.01 m²: F = 10 kg * 9.8 m/s² = 98 N; P= 98/0.01= 9800 Pa
• B. 20 kg, same area: F= 196 N; P= 196/0.01= 19600 Pa
• C. 30 kg, area 20 cm x 20 cm= 0.04 m²: F= 294 N; P= 294/0.04= 7350 Pa
• D. 40 kg, 30 cm x 30 cm= 0.09 m²: F= 392 N; P= 392/0.09≈ 4356 Pa

Order of increasing pressure: D, C, A, B.

Buoyant Forces and Density of Blocks

When considering four blocks submerged in water, the buoyant force depends on the displaced water volume and fluid density: Buoyant force = ρ_fluid × g × V_displaced. The block with the smallest buoyant force displaces the least water, generally correlating with greater density if volume is constant. Since volume is constant here, a denser object will have a higher mass and thus greater weight, but buoyant force depends solely on displaced water volume; thus, identical volumes should experience equal buoyant forces. If the blocks differ in volume or shape, the one with the smallest displaced volume experiences the least buoyant force.

Flow Velocity in Water through Holes

Water flow velocity from holes in a container relates to the height of the water column above each hole. According to Torricelli’s theorem, v = √(2gh), where h is the height of water above the hole. The bottom hole is submerged deeper, thus h is larger, resulting in a higher velocity. This explains why the velocity of water is greater at the bottom outlet, reflecting the influence of gravitational potential energy converting to kinetic energy.

Atmospheric Pressure and Structural Integrity

Regarding the force exerted on a window pane: atmospheric pressure (about 10⁵ Pa) creates a substantial force across a large surface area. The reason the window does not shatter despite this force is due to the structural strength of glass and the relative balance of external atmospheric pressure with internal atmospheric conditions and wind effects. When a strong wind blows, the resultant pressure differential increases, which can lead to increased stress on the window, making it more susceptible to damage if stress exceeds the material’s strength.

Temperature Variations Near Water Bodies and Material Properties

Locations near large water bodies tend to have moderated temperatures because water's high specific heat capacity absorbs and releases heat slowly, buffering temperature fluctuations. This results in milder winters and cooler summers compared to inland areas.

After cleaning with alcohol, a mirror appears colder initially because alcohol evaporates rapidly, absorbing heat from the mirror’s surface, resulting in a cooling sensation. The evaporation process is an endothermic phase change, which removes heat from the surface.

Placing a tub of water in a storage cellar helps prevent food from freezing because water acts as a thermal buffer, absorbing excess cold and maintaining a more stable temperature, preventing temperatures from dropping below freezing.

Touching a wooden pole on a cold day is safe because wood is a poor conductor of heat, offering minimal thermal conduction, whereas metal is a good conductor, rapidly drawing heat away from the tongue, risking tissue damage.

When your hand touches glass displays in the grocery store’s frozen food section, heat is transferred from your hand (warmer) to the cold glass (cooler), causing your hand to feel cold due to heat flow via conduction.

Material Conductivity and Practical Applications

Good conductors of electricity are also good conductors of heat because free electrons in metals facilitate both electrical current and thermal energy transfer. This is why metals like copper are used in electrical wiring and heat sinks (Reitz & Milford, 1995).

Wearing white clothing on hot days reflects more sunlight and absorbs less heat compared to black clothing, leading to a cooler body temperature. This is explained by the principles of blackbody radiation and color absorption characteristics.

Keeping the refrigerator door open on a hot day causes the appliance to work harder, drawing more electrical energy to compensate for the external heat influx, ultimately warming the room rather than cooling it (Çengel & Boles, 2015).

Force, Mass, Weight, and Density Measurements

Standing on a scale with one leg allows less weight to be supported than standing on two legs; however, the scale measures the normal force exerted by your body, which theoretically remains consistent in magnitude, but due to distribution and balance, the displayed reading may slightly vary based on contact area and distribution of mass (Tipler & Mosca, 2008).

A bathroom scale measures the normal force exerted by the person and does not directly measure mass; it reads such force approximations in weight units based on gravitational acceleration.

Water in a lake and a small cup both have the same density because density is an intensive property; it depends on material composition, not volume.

The extremes of temperature are felt more intensely in inland areas—like deserts—where there is less thermal moderation than near oceans or islands which have moderated climates due to ocean’s high specific heat capacity (Hartmann, 2015).

Sand heats up quickly and cools down fast, indicating it has a low specific heat capacity, meaning it cannot store much thermal energy per unit temperature change (Cengel & Boles, 2015).

Water has a high specific heat due to hydrogen bonding, making it able to absorb or release substantial amounts of heat without large temperature changes (Chang, 2014).

When heated from 0°C to 2°C, water first expands until it reaches 4°C, after which it begins to contract slightly upon further heating. Similarly, heating from 4°C to 6°C will cause volume expansion.

Heat transfer via conduction in metals involves free electrons carrying kinetic energy, which leads to efficient thermal conduction (Reitz & Milford, 1995). The process includes collisions of electrons and atoms facilitating energy transfer.

Convection occurs when heated fluid (liquid or gas) moves, transferring heat through bulk motion, evident in boiling water or atmospheric weather patterns.

Refrigeration cools via evaporative cooling: the evaporation of the refrigerant absorbs heat, providing a cooling effect inside the refrigerator (Cengel & Boles, 2015).

References

• Cengel, Y. A., & Boles, M. A. (2015). Thermodynamics: An Engineering Approach (8th ed.). McGraw-Hill Education.
• Chang, R. (2014). Chemistry (11th ed.). McGraw-Hill Education.
• Hartmann, D. L. (2015). Global Physical Climatology. Academic Press.
• Reitz, J. R., & Milford, F. J. (1995). Foundations of Electromagnetic Theory. Addison-Wesley.
• Tipler, P. A., & Mosca, G. (2008). Physics for Scientists and Engineers (6th ed.). W. H. Freeman.