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AlladinOne [14]
3 years ago
12

NASA is giving serious consideration to the concept of solar sailing. A solar sailcraft uses a large, low mass sail and the ener

gy and momentum of sunlight for propulsion. (a) Should the sail be absorbing or reflective
Physics
1 answer:
Stella [2.4K]3 years ago
6 0

Answer:

Reflective

Explanation:

The radiation pressure of the wave that totally absorbed is given by;

P_{abs}= \frac{I}{C}

and While the radiation pressure of the wave totally reflected is given by;

P_{ref}= \frac{2I}{C}

Now compare the two-equation you can clearly see that the pressure due to reflection is larger than absorption therefore the sail should be reflective.

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The average radius of Mars is 3,397 km. If Mars completes one rotation in 24.6 hours, what is the tangential speed of objects on
sammy [17]

Answer: First, we determine the circumference of the Mars by the equation below.  

                                     C = 2πr

Substituting the known values,

                                     C = 2(π)(3,397 km) = 6794π km

To determine the tangential speed, we divide the circumference calculated above by the time it takes for Mars to complete one rotation and that is,

                   tangential speed = 6794π km / 24.6 hours = 867.64 km/h

6 0
2 years ago
Read 2 more answers
A child drops a ball from a window. The ball strikes the ground in 3.0 seconds. What is the velocity of the ball the instant bef
inessss [21]

Answer:

29.396988 m/s

Explanation:

Really, it depends on where the child is when he drops the ball - e.g., which planet he is on, and his distance from the center of that planet.

I'll assume that the child is on Earth at sea level at the equator, so that his distance from the geocenter is 6378000 meters.

The acceleration, g, is found from

g = GM/r²

G = 6.6743e-11 m³ kg⁻¹ sec⁻²

M = 5.9724e+24 kg

r = 6.378e+6 m

g = 9.799086 m sec⁻²

An approximate answer is found from an equation from constant acceleration kinematics:

v = gt

t = 3.0 sec

v = 29.397259 m/s

Now, the above method is an approximation that makes the technically incorrect assumption that the acceleration of gravity is a constant throughout the entire fall. You get away with it because the drop is very short. In another situation, it might not be. So it would be nice to develop a more accurate method that does not assume constant gravitational acceleration. For that, we begin with the Vis Viva equation:

v = √[GM(2/r − 1/a)]

Here,

a = the semimajor axis of a plunge orbit, which is equal to half of the apoapsis distance of 6378000+h, where

h = the altitude from which the ball is dropped

We can (using some math) develop the following equation:

t − t₀ = √[d/(2GM)] { √(rd−r²) + d arctan √(d/r−1) }

t − t₀ = 3 sec

r = 6378000 meters

d = r + h

Using an iterative method (e.g. Newton's or Danby's), we can determine that the altitude,

h = 44.0954 meters

So,

d = 6378044.09538 meters

a = d/2 = 3189022.04769 meters

Now we can calculate that

v = 29.396988 m/s

This is the more nearly correct answer because it takes into account the variability of the gravitational acceleration during the fall.

5 0
2 years ago
Is vapor pressure independent of atmospheric pressure? - This is what my instructor told me, but I don't understand why. ...?
miss Akunina [59]
Vapor pressure<span> or equilibrium </span>vapor pressure<span> is defined as the </span>pressure<span> exerted by a </span>vapor<span> in thermodynamic equilibrium with its condensed phases at a certain temperature. It is independent with atmospheric pressure since it does not change by changing the atmospheric pressure only. </span>
5 0
3 years ago
Where does the energy that is used to ride a bicycle up a hill come from and how is it classified?
MariettaO [177]
Well when you eat you get energy and then you use it to ride up the hill sorry I don't know how it is classified
7 0
3 years ago
Read 2 more answers
A cube-shaped piece of copper has sides of 4cm each and it's density is
iris [78.8K]

Answer:

64 cm^3

Explanation:

<u>Density </u>

The density of a substance is the mass per unit volume. The density varies with temperature and pressure.

The formula to calculate the density of a substance of mass (m) and volume (V) is:

\displaystyle \rho=\frac{m}{V}

We have a cube-shaped piece of copper of 4 cm of side length. The volume of the piece is:

V=(4\ cm)^3=64\ cm^3

Surprisingly, no other magnitude is required, thus the answer is:

\mathbf{64 cm^3}

5 0
2 years ago
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