An object with 15 grams is immersed in benzene and suffers an apparent loss of mass of 5 grams. What is the specific gravity of the object? The specific gravity of benzene is 0.7.
A) 1.4
B) 1.8
C) 2.1
D) 3.0
Actual answer: C
My logic:
Apparent weight = mg - Fb.
=> 10 = 15 - Fb => Fb = 5
=> Fb = pvg = p(object)vg / p(benzene)vg
=> p(object)vg = Fb*p(benzene)vg (1)
sg of benzene = p(benzene)vg / p(water)vg
=> p(water)vg = p(benzene)vg / sg of benzene (2)
(1) / (2) => p(object)/p(water) = [Fb*p(benzene)] / [p(benzene)/sg of benzene] (note: vg/vg and p(benzene)/p(benzene) cancels out)
=> Fb*(sg of benzene) = 5*(0.7) = 3.5
While my logic did not get me to any of the answers, can someone explain what was incorrect about my logic?
A) 1.4
B) 1.8
C) 2.1
D) 3.0
Actual answer: C
My logic:
Apparent weight = mg - Fb.
=> 10 = 15 - Fb => Fb = 5
=> Fb = pvg = p(object)vg / p(benzene)vg
=> p(object)vg = Fb*p(benzene)vg (1)
sg of benzene = p(benzene)vg / p(water)vg
=> p(water)vg = p(benzene)vg / sg of benzene (2)
(1) / (2) => p(object)/p(water) = [Fb*p(benzene)] / [p(benzene)/sg of benzene] (note: vg/vg and p(benzene)/p(benzene) cancels out)
=> Fb*(sg of benzene) = 5*(0.7) = 3.5
While my logic did not get me to any of the answers, can someone explain what was incorrect about my logic?