Answer:
11.25 amps
Explanation:
For transformers, the magnetic flux
Therefore;
Ф = Фmax (cosωt) = 0.21·(cos(5·t))
From Faraday's law of induction, we have;
ε = -N × dΦ/dt
Which gives;
dΦ/dt = -1.05(sin (5t)
)
ε = -N × dΦ/dt = -50× -1.05(sin (5t)
)
ε = 52.5(sin (5t)
)
I = ε/R = 52.5(sin (5t)
)/3.3 = 15.9091(sin (5t)
) amps
The peak current is therefore = 15.9091 amps
The rms current = Peak current /√2 = 15.9091/(√2) = 11.25 amps.
M = 30 g = 0.03 kg, the mass of the bullet
v = 500 m/s, the velocity of the bullet
By definition, the KE (kinetic energy) of the bullet is
KE = (1/2)*m*v²
= 0.5*(0.03 kg)*(500 m/s)² = 3750 J
Because the bullet comes to rest, the change in mechanical energy is 3750 J.
The work done by the wall to stop the bullet in 12 cm is
W = (1/2)*(F N)*(0.12 m) = 0.06F J
If energy losses in the form of heat or sound waves are ignored, then
W = KE.
That is,
0.06F = 3750
F = 62500 N = 62.5 kN
Answer:
(a) 3750 J
(b) 62.5 kN
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