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alekssr [168]
3 years ago
9

When a Lunar Module landed on the Moon, it used thrusters to slow its descent to the surface. When other spacecraft are returned

to Earth, they use parachutes to slow their descent. Why wouldn't a parachute be useful on the Moon?
Physics
1 answer:
katen-ka-za [31]3 years ago
3 0
They had to use thrust because there is no air on the moon meaning that parachutes would be totally useless because parachutes require air to create drag. Fun fact since there is no air on the lunar surface sound waves cannot be made since there are no air molecules for the waves to pass through, so that's why they use radio's in space. 
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A flock of ducks is trying to migrate south for the winter, but they keep being blown off course by a wind blowing from the west
Minchanka [31]

The ducks' flight path as observed by someone standing on the ground is the sum of the wind velocity and the ducks' velocity relative to the wind:

ducks (relative to wind) + wind (relative to Earth) = ducks (relative to Earth)

or equivalently,

\vec v_{D/W}+\vec v_{W/E}=\vec v_{D/E}

(see the attached graphic)

We have

  • ducks (relative to wind) = 7.0 m/s in some direction <em>θ</em> relative to the positive horizontal direction, or

\vec v_{D/W}=\left(7.0\dfrac{\rm m}{\rm s}\right)(\cos\theta\,\vec\imath+\sin\theta\,\vec\jmath)

  • wind (relative to Earth) = 5.0 m/s due East, or

\vec v_{W/E}=\left(5.0\dfrac{\rm m}{\rm s}\right)(\cos0^\circ\,\vec\imath+\sin0^\circ\,\vec\jmath)

  • ducks (relative to earth) = some speed <em>v</em> due South, or

\vec v_{D/E}=v(\cos270^\circ\,\vec\imath+\sin270^\circ\,\vec\jmath)

Then by setting components equal, we have

\left(7.0\dfrac{\rm m}{\rm s}\right)\cos\theta+5.0\dfrac{\rm m}{\rm s}=0

\left(7.0\dfrac{\rm m}{\rm s}\right)\sin\theta=-v

We only care about the direction for this question, which we get from the first equation:

\left(7.0\dfrac{\rm m}{\rm s}\right)\cos\theta=-5.0\dfrac{\rm m}{\rm s}

\cos\theta=-\dfrac57

\theta=\cos^{-1}\left(-\dfrac57\right)\text{ OR }\theta=360^\circ-\cos^{-1}\left(-\dfrac57\right)

or approximately 136º or 224º.

Only one of these directions must be correct. Choosing between them is a matter of picking the one that satisfies <em>both</em> equations. We want

\left(7.0\dfrac{\rm m}{\rm s}\right)\sin\theta=-v

which means <em>θ</em> must be between 180º and 360º (since angles in this range have negative sine).

So the ducks must fly (relative to the air) in a direction 224º relative to the positive horizontal direction, or about 44º South of West.

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goblinko [34]
Your answer is c. electrons that are available for bonding.
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Paraphin [41]
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Who was the proponent of the Neo-classicism?

a) Claude Debussy

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