Physics 102: Fluid And Thermal Physics Exercises 049010

Phy 102 Fluid And Thermal Physics Exercisescomplete The Following Ex

Complete the following exercises related to fluid and thermal physics concepts, including density, pressure, buoyant force, temperature effects, thermal conduction, convection, and properties of materials under different conditions.

Paper For Above instruction

Fluid and thermal physics are fundamental branches of physics that explain the behavior of liquids, gases, and heat transfer processes. These concepts are essential in understanding natural phenomena and industrial applications, ranging from weather patterns to engineering systems. This paper addresses various exercises that explore the principles of density, pressure, buoyancy, thermal expansion, heat transfer, and the physical properties of materials, providing insights into their practical implications.

1. Ranking in terms of increasing density:

Density is defined as mass divided by volume. Calculating the density for each object:

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

Order in increasing density: C (1 g/cm³)

2. Ranking in terms of increasing pressure:

Pressure is force per unit area. For each object:

• A. 10 kg on 10 cm x 10 cm: mass = 10 kg, area = 100 cm², force = mass × gravity ≈ 98 N; Pressure = 98 N / 100 cm² = 0.98 N/cm²
• B. 20 kg on 100 cm²: Force ≈ 196 N; Pressure ≈ 196 N / 100 cm² = 1.96 N/cm²
• C. 30 kg on 400 cm²: Force ≈ 294 N; Pressure ≈ 294 N / 400 cm² = 0.735 N/cm²
• D. 40 kg on 900 cm²: Force ≈ 392 N; Pressure ≈ 392 N / 900 cm² ≈ 0.436 N/cm²

Ordered from smallest to largest pressure: D

3. Smallest buoyant force:

The buoyant force depends on displaced volume, which is identical for all blocks if volume is the same. The density of each block influences buoyant force: less dense blocks are less submerged, experiencing less buoyant force. The block with the highest density will be least submerged and thus experiences the smallest buoyant force.

4. Ranking blocks by increasing density:

Since volume and weight are known, find each density and rank accordingly. The block with the greatest weight in proportion to volume has the highest density.

5. Water flow and velocity:

Applying Bernoulli's principle, water velocity increases at lower heights due to pressure differences and gravitational potential energy conversion. The bottom stream's higher velocity results from greater hydrostatic pressure at lower depths, causing faster outflow.

6. Force on a window pane:

a. The large atmospheric force does not shatter the window because the force is balanced across both sides, resulting in negligible net force; additionally, the window's strength and the distributing pressure prevent shattering.

b. Wind increases pressure differences, potentially exerting higher forces, which may cause damage if the window cannot withstand the increased stress.

7. Temperature variations near large bodies of water:

The high specific heat capacity of water means it heats and cools slowly, moderating temperature fluctuations in nearby land areas, leading to milder winters and cooler summers.

8. Cooling of an alcohol-cleaned mirror:

Evaporation of alcohol absorbs heat from the mirror, cooling its surface immediately after cleaning.

9. Farmer's water tub:

The water acts as a thermal buffer, absorbing heat to prevent the canned food from freezing by maintaining a uniform temperature environment.

10. Thermal conductivity and safety:

Wood is a poor conductor of heat, preventing rapid heat transfer and reducing the risk of frostbite, whereas metal conducts heat efficiently, leading to rapid temperature changes and potential burns.

11. Hand on display case window:

The coolness perceived is due to heat transfer from the warmer hand to the cooler glass, causing the hand to become cold through conduction.

12. Conductivity of materials:

Good electrical conductors are also good thermal conductors because free electrons facilitate both electrical and thermal energy transfer efficiently.

13. Wearing white vs. black shirts:

White reflects most of the sunlight, reducing heat absorption, while black absorbs more heat, making it hotter to wear.

14. Refrigerator door open:

Opening the fridge introduces warmer room air, causing the compressor to work harder, thus warming the room rather than cooling it effectively.

15. Scale reading on one foot vs. two:

Standing on one leg reduces the area of contact, increasing the pressure (force per unit area), but the scale measures the normal force – so the reading remains the same.

16. What a bathroom scale measures:

The scale measures the force exerted by the person due to gravity (weight).

17. Density comparison:

The density is independent of the amount of water; both the lake and the cup contain the same water with identical density.

18. Temperature extremes:

Inland areas, such as deserts, experience greater temperature swings due to lack of large bodies of water to buffer temperature changes.

19. Hot and cold desert sand:

The sand’s low specific heat causes rapid temperature changes, heating quickly during the day and cooling rapidly at night.

20. Highest specific heat:

Water has the highest specific heat capacity among the options, allowing it to absorb and store large amounts of heat.

21. Effect of heating on water volume (0°C to 2°C):

Water’s volume initially decreases when cooled below 4°C, but from 0°C to 2°C, due to anomalous expansion, it may slightly increase; overall, it generally decreases with heating in this narrow range.

22. Heating water from 4°C to 6°C:

The volume increases slightly as water warms above 4°C, approaching its maximum density at 4°C.

23. Heat conduction in metals:

Conduction occurs primarily via electrons transferring kinetic energy during collisions with each other and atoms.

24. Convection heat transfer:

Occurs when mass movement of fluids—like water or air—carries heat away from hot regions.

25. Cooling in refrigerators:

The evaporation of refrigerant absorbs heat from inside the refrigerator, producing the cooling effect.

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