A shaving brush is dipped in water. When taken out, the hairs of the brush are seen to be drawn together due to:
- Asurface tension of water
- Bviscosity of water
- Celasticity of the hairs of the brush
- Dtemperature difference between air and water
Solution & Step-by-step Explanation
When the shaving brush is inside the water, water surrounds all the hairs uniformly, allowing them to remain spread apart. However, when the brush is pulled out of the water, a thin liquid film forms across the outer boundary of the hairs. Surface tension causes the free surface of this liquid film to contract to minimize its surface area, pulling the individual hairs close together.