A rectangular aluminium solid block of density 2700kg/m3 has dimensional of 40cm ×12cm×6cm.the rests on a horizontal flat surface area calculate minimum and maximum pressure
Answers
Answer:
ANSWER
Given, mass of place of aluminium, m=1kg;
density of aluminium, ρ
s
=2700kg/m
3
;
density of water, ρ
w
=1000kgm
−3
As shown in figure, we have to find tension in the string in each case.
(a) When the aluminium piece is suspended in air
Tension, T=mg [Ref fig. (a)]
or T=1×10=10N
(b) When the aluminium piece is completely immersed in water,
mg=T+F
B
[Ref fig.(b)]
Where, F
B
= buoyant force acting on aluminium
T= tension in the string
∴T=mg−F
B
=ρ
s
V
s
g−ρ
L
V
L
g
=(ρ
s
V
s
−ρ
L
V
L
)g
=(ρ
s
V
s
−ρ
L
V
s
)g
=ρ
s
V
s
(1−
ρ
s
ρ
L
)g=(ρ
s
V
s
g)(1−
ρ
s
ρ
L
)
=mg(1−
ρ
s
ρ
L
)
or T
′
=1×10(1−
2700
1000
)=10(1−
27
10
)
or T
′
=10(
27
27−10
)=10(
27
17
)
=6.296N.
Hence, the tension in the string before and after the metal is immersed are 10N and 6.296N respectively.
