Match on water sustained by surface tension

The difference in surface tension between the water and the soap, which creates a net force on the match. In summary, a match of length 4cm is floating on the surface of water at room temperature. When a few drops of soap are poured on one side of the match, it starts moving towards the pure water due to a difference in surface tension between the water and soap. The force acting on the match can be calculated using the equation F= (sigma water - sigma soap) * l.
  • #1
RingNebula57
56
2

Homework Statement


A match of length l=4cm is floating on the surface of the water from a glass. ( the water is at room temperature) If from on one side of the match we pour a few drops of soap, the match starts moving. In which direction is the match mooving and what force is acting upon it? ( sigma (water) = 73 mN/m ; sigma (soap) = 43 mN/m)

Homework Equations


F= sigma * l

The Attempt at a Solution


The force acting on the match is F= (sigma water - sigma soap) * l. I don't fully uderstand how the phenomenon is going on ... could someone draw what's happening in this problem ?

thank you!
 
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  • #2
RingNebula57 said:
which direction is the match mooving
 
  • #3
towards the pure water
 
  • #4
What causes that?
 

1. What is surface tension?

Surface tension is the attractive force between molecules on the surface of a liquid that causes the surface to behave like a thin, elastic film. It is created by the imbalance of forces between the molecules on the surface and those within the liquid.

2. How does surface tension allow for matches to be sustained on water?

The surface tension of water allows for an invisible skin to form on the surface, making it more difficult for objects to penetrate or sink into the water. The surface tension can support the weight of objects, such as a match, that are less dense than water.

3. Can any type of match be sustained on water by surface tension?

No, only certain types of matches can be sustained on water by surface tension. The match head must be small and made of a light material, such as wood or cardboard, in order for the surface tension to support it.

4. Is the surface tension of water strong enough to hold multiple matches?

Yes, the surface tension of water is strong enough to hold multiple matches as long as the weight of the matches does not exceed the surface tension force of the water. This can be affected by factors such as the size and weight of the matches, as well as any impurities or substances on the surface of the water.

5. Why does a match on water eventually sink?

A match on water will eventually sink because the surface tension of water is not strong enough to support the weight of the match indefinitely. Over time, the match will absorb water and become heavier, causing it to break through the surface tension and sink.

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