a) Define the term surface tension (b) Calculate the force required to lift a needle...

PHYSICS
WAEC 2000

a) Define the term surface tension

(b) Calculate the force required to lift a needle 4cm long off the surface of water if the surface tension of water is 7.3 x 10\(^{-4}\) NM\(^{-1}\)

Explanation

a) Surface tension is defined as a force per unit length perpendicular to any line on the surface of the liquid OR Property of a liquid which makes the surface of liquid behave like an elastic skin.

(b) Surface tension = F/21

=7.3 x 1\(^{-2}\) x 2 x 0.04 = 5.8 x 10\(^{-3}\)N



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