Which freezes faster, hot water or cold water?
2 answers:
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Answer:
E.) conservation of angular momentum
Explanation:
The angular momentum is defined as:
x
where is the radius of the star,
is the mass and
the angular velocity.
and angular momentum is an amount that is conserved, so the angular momentum before the star is compressed must be equal to the angular momentum after the star was compressed:
x
x
the second radius is smaller than the first radius, since the star shrinked, the second angular velocity must be greater that the first.
In other words, the angular velicity increases as the star shrinks because of the conservation of angular momentum.
Answer:
= 1.75 × 10⁻⁴ m/s
Explanation:
Given:
Density of copper, ρ = 8.93 g/cm³
mass, M = 63.5 g/mol
Radius of wire = 0.625 mm
Current, I = 3A
Area of the wire, =
Now,
The current density, J is given as
= 2444619.925 A/mm²
now, the electron density,
where,
=Avogadro's Number
Now,
the drift velocity,
where,
e = charge on electron = 1.6 × 10⁻¹⁹ C
thus,
= 1.75 × 10⁻⁴ m/s