9: A post is being driven into the ground. The first strike drives the post 25 inches into the ground. Each additional strike dr
1 answer:
Answer:
99
Explanation:
First strike=25 in
Second strike=4/5*25=20 in
Third strike=4/5*20=16 in
Fourth strike=4/5*16=12.8 in
Fifth strike=4/5*12.8=10.24 in
sixth strike=4/5*10.24=8.192 in
seventh strike=4/5*8.192=6.5536 in
Total=(25+20+16+12.8+10.24+8.192+6.5536) in=98.7856 in
Taking this as a geometric series
where a is initial value taken as 25 for this case and r is rate taken as 4/5 or 0.8 in our case
To the nearest inches, sum is 99 in
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Answer:
(a): .
(b): 20.94 Volts.
Explanation:
<u>Given:</u>
- Area of the coil = A.
- Number of turns of the coil = N.
- Magnetic field in which the coil is placed = B.
- The frequency with which the coil is rotating = f.
The magnetic flux linked with a coil is defined as
where,
is the area vector of the coil, directed along the normal to the plane of the coil.
= angle between the magnetic field and the area vector of the coil.
Assuming that the magnetic field is along the normal to the plane of the coil, initially.
Therefore, at any later time t, the angle which the magnetic field makes with the normal to the plane of the coil is is given by
Therefore, the magnetic flux linked with the coil at any time t is given by
According to the Faraday's law of electromagnetic induction, the emf induced in the coil is given by
The amplitude of the alternating voltage is the maximum value of the induced emf in the coil, the induced emf in the coil is maximum when .
Therefore, the amplitude of the alternating voltage is given by
Given values are:
- N = 100 turns.
- A =
.
- B = 0.1 T.
- f = 2000 rev/min =
Putting all these values,