<span>If the wire is then wound into a coil, the magnetic field is greatly intensified producing a static magnetic field around itself forming the shape of a bar magnet giving a distinct North and South pole.
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Answer:
The ratio of kinetic energies of 5 kg object to 20 kg object is 1:1.
Explanation:
Kinetic energy is defined as energy possessed by an object due to its motion.It is calculated by:

Kinetic energy of the 5 kg object.
Mass of object,m = 5 kg
Velocity of an object = v

Kinetic energy of the 20 kg object.
Mass of object,m' = 20 kg
Velocity of an object = v'

The ratio of the kinetic energy of the 5 kilogram object to the kinetic energy of the 20-kilogram object:

Given that, v = 2v'

The ratio of kinetic energies of 5 kg object to 20 kg object is 1:1.
Answer:
<em>Details in the explanation</em>
Explanation:
<u>Vertical Launch</u>
When an object is thrown vertically in free air (no friction), it moves upwards at its maximum speed while the acceleration of gravity starts to brake it. At a given time and height, the object stops in mid-air and starts to fall back to the launching point until reaching it with the same speed it was launched.
We are given an expression for the height of an object in function of time t

<em>Please note we have deleted the second 'squared' from the formula since it's incorrect and won't describe the motion of vertical launch.</em>
We now have to evaluate h for the following times, assuming h comes in feet
At t=1 sec

The object is at a height of 48 feet
At t=2 sec

The object is at a height of 64 feet. This is the maximum height the object will reach, as we'll see below
At t=3 sec

The object is at a height of 48 feet. We can clearly see it's returning from the maximum height and is going down
At t=4 sec

The object is at ground level and has returned to the launch point.
Answer:
0.233
Explanation:
Given that
Diameter of rotor, d = 40 m
Power of rotor, P = 90 kW
Speed of the wind, v = 8 m/s
Density of air, p = 1.2 kg/m³
It is a known fact that
KE = ½mv², where mass flow rate, m
m = p.A.v, where Area, A
A = πd²/4
A = (3.142 * 40²)/4
A = 3.142 * 1600/4
A = 3.142 * 400
A = 1256.8 m², substitute for A in the mass flow rate equation
m = p.A.v
m = 1.2 * 1256.8 * 8
m = 12065.28, substitute for m in the KE equation
KE = ½mv²
KE = ½ * 12065.28 * 8²
KE = 12065.28 * 32
KE = 386088.96 W or
KE = 386.1 kW
Fraction of kinetic energy converted to electric energy is
Fraction = Electric Power / Total KE
Fraction = 90 / 386.1
Fraction = 0.233