FISIKA Kelas 11 - Tegangan Permukaan | GIA Academy

Introduction

This tutorial focuses on the concept of surface tension, as explored in the video "FISIKA Kelas 11 - Tegangan Permukaan" by GIA Academy. Understanding surface tension is crucial for grasping various physical phenomena and its applications in everyday life. This guide will break down key concepts, formulas, and practical examples related to surface tension, making it easier to comprehend and apply.

Step 1: Understanding Surface Tension

• Definition: Surface tension is the force that causes the surface of a liquid to behave like a stretched elastic membrane. It arises from the cohesive forces between liquid molecules.
• Importance: Surface tension is significant in various natural processes, such as the formation of droplets and the ability of certain objects to float on water.

Step 2: Key Concepts of Surface Tension

• Cohesive Forces: These are the intermolecular forces that hold the liquid molecules together, contributing to surface tension.
• Surface Molecules: Molecules at the surface experience a net inward force, leading to the formation of a surface that minimizes area.

Step 3: Formula for Surface Tension

• The formula for calculating surface tension (γ) is given by:

  γ = F / L
  

  Where:

  • F = force acting along the surface (in Newtons)
  • L = length along which the force acts (in meters)

Step 4: Factors Affecting Surface Tension

• Temperature: As temperature increases, surface tension generally decreases.
• Impurities: The presence of surfactants (like soap) lowers surface tension by disrupting cohesive forces.
• Nature of the Liquid: Different liquids have varying levels of surface tension based on their molecular structure.

Step 5: Surface Tension in Practical Applications

• Capillary Action: This phenomenon occurs when liquid rises in a narrow space due to surface tension. It is essential in plant water absorption.
• Droplet Formation: Surface tension causes liquids to form spherical droplets, minimizing surface area and energy.

Step 6: Experiment with U-Shaped Wire

• Objective: Demonstrate surface tension using a U-shaped wire.
• Procedure:
  1. Place the U-shaped wire in a liquid (like water).
  2. Observe the wire's interaction with the water surface.
  3. Note how the liquid bends around the wire due to surface tension.

Step 7: Solving Surface Tension Problems

• Example Problem: If a force of 0.2 N acts along a 0.1 m length of a surface, calculate the surface tension.

  γ = F / L
  γ = 0.2 N / 0.1 m = 2 N/m
  

• Practice Problems: Try solving various problems involving different forces and lengths to solidify your understanding.

Conclusion

In this tutorial, you learned about the fundamental concepts of surface tension, its formula, influencing factors, and practical applications. To further your understanding, consider conducting simple experiments or solving additional problems related to surface tension. Engaging with real-world examples will enhance your grasp of this essential physics concept.