Mercury refuses to wet solid glass surfaces due to a specific liquid property referred to as__________________?
Show answer Hide answer
Answer: C. surface tension
Explanation
Surface tension arises from unbalanced molecular cohesive forces acting at the liquid-gas boundary. Cohesive forces between mercury atoms are significantly stronger than adhesive forces between mercury and glass. This strong internal cohesion causes mercury droplets to minimize their surface area and form convex shapes. Cohesion refers to the intermolecular attraction between like molecules within the same liquid substance. Adhesion describes the attractive force between dissimilar molecules, such as liquid and solid container walls. Contact angles greater than ninety degrees indicate non-wetting behavior typical of mercury on glass.
Non-wetting behavior causes mercury to roll in spherical droplets without leaving a wet film behind. This property affects the meniscus shape in glass barometers, requiring specific reading corrections. Understanding surface tension is crucial for analyzing fluid flow, droplet formation, and capillarity phenomena. Adhesion represents attractive forces between unlike molecules, which would promote wetting rather than repelling. Viscosity measures fluid resistance to gradual shear deformation and flow rather than surface wetting. Compressibility quantifies volume changes under applied hydrostatic pressure and does not govern wetting.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
Related questions
Q1. Transverse fillet welded connections are structurally proportioned to resist________________?
Show answer Hide answer
Answer: A. tensile strength
Transverse fillet welded connections are structurally analyzed and proportioned based on resisting tensile or shear stresses depending on leg orientation.
Q2. The largest thermal energy loss occurring within an industrial boiler is attributed to _______________________?
Show answer Hide answer
Answer: D. flue gases
Hot flue gases exiting the boiler exhaust stack carry away massive amounts of sensible heat. This thermal energy loss represents the single largest inefficiency in industrial boiler operation. High exit temperatures mean...
Q3. What is the maximum solubility limit percentage of carbon dissolved in ferrite___________________?
Show answer Hide answer
Answer: A. 0.025%
The maximum solid solubility limit of carbon in alpha-ferrite at the eutectoid temperature is very low, approximately 0.025%. Because body-centered cubic ferrite has restricted interstitial spaces, it can accommodate onl...
Q4. Out of the choices below, which pipe joint design is most appropriate for high-pressure steam lines_____________?
Show answer Hide answer
Answer: D. expansion
Expansion joints incorporate flexible bellows or sliding sleeves to absorb thermal dimensional changes. High-pressure steam pipelines experience significant temperature fluctuations during startup and shutdown cycles. Wi...
Q5. Identify the technique that does NOT serve as a valid method for raising the fatigue limit_______________?
Show answer Hide answer
Answer: C. surface decarburisation
Surface decarburisation depletes carbon from the outer metal layer, reducing hardness and strength. Lower surface carbon creates weak microstructural zones that readily initiate fatigue cracks. Since it degrades fatigue...
Q6. The included notch angle machined on a standard Izod impact test specimen measures________________?
Show answer Hide answer
Answer: D. 45°
The standard Izod impact test specimen is machined with a 45-degree included notch angle. This precise notch geometry creates a severe triaxial stress state and localized stress concentration during impact testing. Stand...