Surface tension is a property of liquids that allows them to minimize surface area, demonstrated by water droplets forming shapes influenced by gravity. Insects like the water strider can walk on water due to their weight distribution, which prevents them from breaking the surface tension. Objects like needles can float on water despite being denser because the surface tension counteracts gravity's pull.

1. Ms. M. Karthika,
Asst Professor,
Dept of physics,
Bon Secours College For Women
SURFACE TENSION

2. What is Surface tension?
Surface tension is that property of liquids owing to
which they tend to acquire minimum surface area.
Surface tension = Force/ length
Unit of Surface tension : newton per metre.

3. What is the shape of the water drop?

4. When using a water dropper, the water does not
flow in a continuous stream, but rather in a series
of drops. How ?
The shape of the drops is caused by the surface
tension of the water.
The only reason the drop of water isn't
completely spherical is that the force of gravity
pulling down on it.
In the absence of gravity, the drop would
minimize the surface area in order to minimize
tension, which would result in a perfectly
spherical shape.

5. Does the insect is walking on the water?

6. Yes, Insects walking on water.
Several insects are able to walk on water, such as
the water strider.
Their legs are formed to distribute their weight,
causing the surface of the liquid to become depressed,
minimizing the potential energy to create a balance of
forces so that the strider can move across the surface
of the water without breaking through the surface.

7. Why the needle is floating in
water?

8. Needle (or paper clip) floating on
water.
Even though the density of these
objects is greater than water,
the surface tension along the
depression is enough to counteract the
force of gravity pulling down on the
metal object.