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Difficulty: EasyPhysics Fundamentals and Everyday Applications

Surface tension is an important property of liquids observed in daily life. Which of the following everyday phenomena are directly caused by surface tension? Select all the correct statements.

  1. Raindrops acquiring a spherical shape as they fallAnswer
  2. Small insects like water striders walking across the surface of a pondAnswer
  3. C
    A straight straw appearing bent when placed partially in a glass of water
  4. D
    The shimmering illusion of water on a hot asphalt road surface

Answer

Raindrops forming spherical shapes and water striders walking on water surfaces are both direct manifestations of liquid surface tension.
Raindrops acquiring a spherical shape and small insects walking on water are both direct manifestations of surface tension. Cohesive forces draw surface liquid molecules inward, giving droplets a minimal surface area shape (a sphere) and creating a tensile film strong enough to support small insects.

Step-by-Step Solution

1
Define surface tension and identify its physical characteristics.
Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible owing to cohesive forces among molecules.
Understanding the fundamental cause of surface tension helps evaluate its everyday effects.
2
Evaluate the choices related to fluid behavior.
A sphere has the minimum surface area for a given volume, so falling raindrops become spherical. Cohesive forces also create a surface layer that supports light objects such as water striders.
Both behaviors minimize surface energy and demonstrate surface tension.
3
Evaluate optical choices.
The apparent bending of objects in water and road mirages are optical phenomena driven by light refraction and total internal reflection.
These effects depend on light propagation speeds through different media, not cohesive liquid forces.

Key Concept

Surface tension in liquids due to intermolecular cohesive forces
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Topics

Physics Fundamentals and Everyday Applications

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