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Marrrta [24]
3 years ago
5

A helicopter, starting from rest, accelerates straight up from the roof of a hospital. The lifting force does work in raising th

e helicopter. An 790-kg helicopter rises from rest to a speed of 7.0 m/s in a time of 3.0 s. During this time it climbs to a height of 7.2 m. What is the average power generated by the lifting force?
Physics
1 answer:
LuckyWell [14K]3 years ago
6 0

Answer:

25032.47 W

Explanation:

Power is the time rate of doing work, hence,

P = Work done(non conservative) / time

Work done (non conservative) is given as:

W = total K. E. + total P. E.

Total K. E. = 0.5mv²- 0.5mu²

Where v (final velocity) = 7.0m/s, u (initial velocity) = 0m/s

Total P. E. = mgh(f) - mgh(i)

Where h(f) (final height) = 7.2m, h(i) (initial height) = 0 m

=> W = 0.5mv² - mgh(f)

P = [0.5mv² - mgh(f)] / t

P = [(0.5*790*7²) - (790*9.8*7.2)] / 3

P = (19355 + 55742.4) / 3 = 75097.4/3

P = 25032.47 W

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1 = (1/2)*(2*10⁻⁶)V²
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6 0
3 years ago
In traveling a distance of 2.5 km between points A and D, a car is driven at 99 km/h from A to B for t seconds and 48 km/h from
Andreyy89

Answer:

d = 1.954 Km

Explanation:

given,

total distance, D = 2.5 Km

in stretch A to B =

speed = 99 Km/h = 99 x 0.278 = 27.22 m/s     time =t

in stretch B to C

time = 3.4 s

In stretch C to D

speed = 48 Km/h = 48 x 0.278 = 13.34 m/s     time =t      

we know,

distance = speed x time

distance of BC

using equation of motion

v = u + a t

27.22 = 13.34 - a x 3.4

a = 4.08 m/s²

uniform deceleration is equal to 4.08 m/s²

distance traveled in BC

s = ut + \dfrac{1}{2}at^2

s = 13.34\times 3.4 + \dfrac{1}{2}\times 4.08 \times 3.4^2

s = 68.94 m

3000 = 99 \times \dfrac{1000\ t}{3600}+ 68.94 + 48\times \dfrac{1000\ t}{3600}

3000 = 27.5 t + 68.94 + 13.33 t

40.83 t = 2931.06

t = 71.79 s

distance travel in AB

distance = s x t

d = 27.22 x 71.79

d = 1954 m

d = 1.954 Km

distance between A and B is equal to 1.954 Km.

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Answer:

d

Explanation:

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A paperweight consists of a 8.55-cm-thick plastic cube. Within the plastic a thin sheet of paper is embedded, parallel to opposi
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Answer:

\mu=1.5322

Explanation:

Given:

Thickness of the paperweight cube, x=8.55\ cm

apparent depth from one side of the inbuilt paper in the plastic cube, i=4.02\ cm

apparent depth from the other side of the inbuilt paper in the plastic cube, i'=1.56\ cm

Now as we know that refractive index is given as:

\rm \mu=\frac{real\ depth}{apparent\ depth}

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Since refractive index for an amorphous solid is an isotropic quantity so it remains same in all the direction for this plastic.

\mu=\mu'

\frac{d}{i} =\frac{d'}{i'}

\frac{d}{4.02}=\frac{8.55-d}{1.56}

d=6.1597\ cm

Now the refractive index:

\mu=\frac{d}{i}

\mu=\frac{6.1596}{4.02}

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Theory is a guess that consists of something a group of people believe to be true a hypothesis is an educated guess

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