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faltersainse [42]

3 years ago

12

An 80 kg man descends to the ground from an aeroplane using a parachute. If the drag coefficient of the parachute is 0.5 and the

density of air is 1.35 kg/m3, calculate the required diameter of the parachute so that the man descends with a velocity of 25 m/s.

1 answer:

xeze [42]3 years ago

8 0

Answer:

Explanation:2.17 m

Given

Mass of man=80 kg

drag coefficient $(c_D)=0.5$

Density of air $=1.35 kg/m^3$

Required descend velocity(v)=25 m/s

Let d be the diameter of Parachute

In this case Drag force will oppose weight of man so that net force is zero and there is a constant velocity of descend

$W=F_L$

$F_L=\frac{c_DA\rho v^2}{2}$

W=mg

$80\times 9.81=\frac{0.5\times \frac{\pi d^2}{4}\times 1.35\times 25^2}{2}$

$784.8=165.691\times d^2$

d=2.17 m

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Answer:

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Answer:

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According to Maxwell's equation which is expressed as;

V(t) = dФ/dt ........(1)

Magnetic flux Ф can also be expressed as;

Ф = LI(t)

Where

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We can therefore Express Maxwell equation as:

V(t) = dLI(t)/dt ....... (2)

Since the inductance is constant then voltage remains

V(t) = LdI(t)/dt

In an AC circuit, the current is time varying and it is given in the form of

I(t) = I₀sin(ωt)

Substitutes the current I(t) into equation (2)

Then the voltage across inductor will be expressed as

V(t) = Ld(I₀sin(ωt))/dt

V(t) = LI₀ωcos(ωt)

Where cos(ωt) = sin(π/2 - ωt)

Then

V(t) = ωLI₀sin(π/2 - ωt) .....(3)

Because the voltage and current are out of phase with the phase difference of π/2 or 90°

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