15. Find the speed of a disc of radius 0.5 meters and mass 2-kg at the base of the incline. The disc starts at rest and rolls do
1 answer:
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Answer: a) 1 b) 61 W c) 61 W
Explanation:
a) The Power Factor (also known as cos φ), is defined by the difference in phase between current and voltage, in a RLC series circuit, and is expressed as follows:
cos φ = R / Z = R /
In resonance, XL =XC, so the circuit behaves like it were purely resistive, so Z=R.
Replacing in the expression for power factor, we have:
cos φ = R/Z = R/R = 1
This means that in resonance, current and voltage are in phase each other.
b) The average power delivered by the source, in resonance, is simply the power dissipated at the resistance R, as follows:
Pavg = V² rms / R = V₀² / √2 / R = 61 W
c) If the circuit remains in resonance, the average power , which does not depends on frequency provided this condition remains, keeps the same, i.e. , 61 W.
Answer:
Explanation:
The strength of the electric field produced by a charge Q is given by
where
Q is the charge
r is the distance from the charge
k is the Coulomb's constant
In this problem, the electric field that can be detected by the fish is
and the fish can detect the electric field at a distance of
Substituting these numbers into the equation and solving for Q, we find the amount of charge needed: