False because opposites attract. :)
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The self inductance can be calculated as 4.444 Henry.
The inductor will store energy = 20 joule,
current = 3 ampere.
<h3>What is Self inductance?</h3>
The current carrying conductor which allows or opposes the change of flow of current is known as self-inductance. The rate of change of current can also be given through self inductance.
Formula can be given for the energy in the inductor as,
E = 1 / 2 × L × I² joule.
where as, E - Energy
L - Inductance
I - Current flowing through the coil.
The equation can be rearranged as,
L = 2 E/ I²
= 2 × 20 / 3²
= 40 / 9
Hence, L = 4.4444 Henry
Learn more about energy in inductors,
brainly.com/question/28030901
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The force exerted on the rope of the pulley system if the rope is pulled for 24 m in order to raise the mass to the required height is 81.6 N
<u>Explanation:</u>
Efficiency, γ = 64%
mass, m = 78 kg
height, h = 4 m
Force, F = ?
distance of the rope pulled, x = 24 m
We know,
Acceleration due to gravity, g = 9.81 m/s²
Potential energy, PE = mgh = (78) X (9.81) X (4) = 3060.72 joules
Work, W = F X x
F = W/d = (3060.72) / (24) = 127.53 N
However, the efficiency of the pulley system is 64%.
The real force required is F(net) = (127.53) X (0.64) = 81.6 N
Therefore, the force exerted on the rope of the pulley system if the rope is pulled for 24 m in order to raise the mass to the required height is 81.6 N