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Question
A horizontal force of 0.5 N is required to move a metal plate of area 10−2 m2 with a velocity of 3 × 10−2m/s, when it rests on 0.5 × 10−3 m thick layer of glycerin. Find the coefficient of viscosity of glycerin.
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Solution
Given:
F = 0.5 N = 5 × 10−1
A = 10−2 m2,
dv = 3 × 10−2 m/s
dx = 0.5 × 10−3 m = 5 × 10−4 m
To find:
The coefficient of viscosity of glycerin (η) = ?
Formula:
`eta = F/(A(dv)/(dx))`
= `(5 xx 10^-1)/(10^-2 xx ((3 xx 10^-2)/(5 xx 10^-4))`
= `(5 xx 10^-1)/10^-2 xx (5 xx 10^-4)/(3 xx 10^-2)`
= `25/3 xx 10^-1`
= 8.33 × 10−1
∴ η = 0.833 Ns/m2
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