Answer:
ρ = 7500 kg/m³
Explanation:
Given that
mass ,m = 12 kg
Displace volume ,V= 1.6 L
We know that
1000 m ³ = 1 L
Therefore V= 0.0016 m ³
When metal piece is fully submerged
We know that
mass = Density x volume

Now by putting the values in the above equation

ρ = 7500 kg/m³
Therefore the density of the metal piece will be 7500 kg/m³.
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Answer:
The fraction fraction of the final energy is stored in an initially uncharged capacitor after it has been charging for 3.0 time constants is

Explanation:
From the question we are told that
The time constant 
The potential across the capacitor can be mathematically represented as

Where
is the voltage of the capacitor when it is fully charged
So at


Generally energy stored in a capacitor is mathematically represented as

In this equation the energy stored is directly proportional to the the square of the potential across the capacitor
Now since capacitance is constant at
The energy stored can be evaluated at as


Hence the fraction of the energy stored in an initially uncharged capacitor is
