Derive the relationships of pressure difference with surface tension for droplet and bubble…
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Derive the relationships of pressure difference with surface tension for droplet and bubble. Use scaling law to explain why a water strider can walk on water, but elephant cannot.
1P= 2T / R for droplet
1P = 4T / R for bubble.
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Technifi Expert’s Answer:
The pressure force inside balances the force due to surface tension at the edge.
Pressure Force = Surface Tension Force
PπR2 = 2πRT
P = 2T/R
Bubble has two edges. Therefore,
Pressure Force = 2 x Surface Tension Force
PπR2 = 2(2πRT)
P = 4T/R
Water Strider can walk due to its legs. The legs have ting hairs that repel water and capture hairs. As a result of water repelling, water striders can stand on the water surface. While the captured hairs allow them to float and mover easily.
The Elephants on the other hand cannot create that much repel force by using their legs to repel their weight.
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