Answer: a) B = 6811N
b) m = 603.2kg
c) 86.8%
Explanation: <em>Buoyant force</em> is a force a fluid exerts on a submerged object.
It can be calculated as:

where:
is density of the fluid the object is in;
is volume of the object;
g is acceleration due to gravity, is constant and equals 9.8m/s²
a) For the hollow plastic sphere, density of water is 1000kg/m³:

B = 6811N
b) Anchored to the bottom, the forces acting on the sphere are <u>Buoyant</u>, <u>Tension</u> and <u>Force due to gravity</u>:
B = T + 
B = T + mg
mg = B - T

Calculating:

m = 603.2kg
c) When the shpere comes to rest on the surface of the water, there are only <u>buoyant</u> <u>and</u> <u>gravity</u> acting on it:
B = m.g



= 0.6032m³
Fraction of the submerged volume is:
=
= 0.868
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