We employed the pressure P formulas. the reading of the balance when the body is;
a. In air = 29.4 N
b. Fully immersed in water = 3.9 N
c. ⅓ immersed in water = 20.9 N
d. Fully immersed in paraffin = 3.1 N
Given that a body of mass 3kg and volume 4×10^-4m^3 is hung from balance graduated in newtons. To know the reading of the balance when the body is;
a. In air
b. Fully immersed in water
c. ⅓ immersed in water
d. Fully immersed in paraffin.
We will employ the pressure P formulas.
P = F/A
and
P = ρgh
Where
ρ = density
g = acceleration due to gravity
h = height
F = force
A = area
F/A = ρgh
Cross multiply
F = ρghA
Where hA = Volume V
Therefore, F = ρgV
a. In air
F = mg
F = 3 x 9.8
F = 29.4 N
b. Fully immersed in water
F = ρgV
F = [tex]10^{3}[/tex] x 9.8 x 4 x [tex]10^{-4}[/tex]
F = 3.92 N
c. ⅓ immersed in water
F = (ρgV)/3 + 2/3(mg)
F = 3.92/3 + (2/3 x 29.4)
F = 1.3067 + 19.6
F = 20.9N
d. Fully immersed in paraffin.
F = ρgV
F = 800 x 9.8 x 4 x [tex]10^{-4}[/tex]
F = 3.136 N
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