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AnnyKZ [126]
3 years ago
11

We can detect 21-cm emission from other galaxies as well as from our own Galaxy. However, 21-cm emission from our own Galaxy fil

ls most of the sky, so we usually see both at once. How can we distinguish the extragalactic 21-cm emission from that arising in our own Galaxy? (Hint: Other galaxies are generally moving relative to the Milky Way.)
Physics
1 answer:
amid [387]3 years ago
6 0

Answer:

Explanation:

Galaxies are in constant motion with respect to each other . For example Andromeda galaxy is approaching our galaxy ( milky way ) at about 110 km /s . So we will observe blue shift in the spectrum of radiation coming from  this galaxy . In this way, we can distinguish between radiation coming from our galaxy and that coming from other galaxy . Spectrum of radiation coming from other galaxy must  have either red or blue  shift .

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The driver of a car slams on the brakes when he sees a tree blocking the road. The car slows uniformly with acceleration of −5.2
sergejj [24]

Answer:

The car strikes the tree with a final speed of 4.165 m/s

The acceleration need to be of -5.19 m/seg2 to avoid collision by 0.5m

Explanation:

First we need to calculate the initial speed V_{0}

x=V_{0} *t+\frac{1}{2} *a*(t^{2} )\\62.5m=V_{0} *4.15s+\frac{1}{2} *-5.25\frac{m}{s^{2} } *(4.15^{2} )\\V_{0}=25.953\frac{m}{s}

Once we have the initial speed, we can isolate the final speed from following equation:

V_{f} =V_{0} +a*t  V_{f}= 4.165 \frac{m}{s}  

Then we can calculate the aceleration where the car stops 0.5 m before striking the tree.

To do that, we replace 62 m in the first formula, as follows:

x=V_{0} *t+\frac{1}{2} *a*(t^{2} )\\62m=25.953\frac{m}{s}*4.15s+\frac{1}{2} *-a\frac{m}{s^{2} } *(4.15^{2} )\\a=-5.19\frac{m}{s^{2} }

3 0
3 years ago
Read 2 more answers
Using an unmanned rocket to visit the space station requires 85.2 trillion BTU of energy. The best fuel for the mission will hav
Illusion [34]
We shall convert all of the densities to lbs/gal, so the product of
BTU/lbs and lbs/gal gives us the basis of comparison, which was "ratio of energy to volume".
grams / ml x 1 lbs/454 grams → 1 lbs/ 454 ml
1 lbs/454 ml x 3785.41 ml/gal → 3785.41 lbs/454gal
Conversion of g/ml = 8.34 lbs/gal
Looking at each fuel:

Kerosene:
18,500 x (8.34 x 0.82) = 126,517 BTU/gal

Gasoline:
20,900 x (8.34 x 0.737) = 128,463 BTU/gal

Ethanol:
11,500 x (8.34 x 0.789) = 75,673 BTU/gal

Hydrogen:
61,000 x (8.34 x 0.071) = 36,120 BTU/gal

The best fuel in terms of energy to volume ratio is Gasoline.
Gallons required:
BTU needed / BTU per gallon
= 85.2 x 10⁹ / 128,463
= 6.6 x 10⁵ gallons
5 0
3 years ago
A force of 15 newtons is used to push a box along the floor a distance of 3 meters. How much was done?
bezimeni [28]

Answer:

45 J

Explanation:

The equation for work is:

Work=Force*Distance

We can substitute the given values into the equation:

Work=15N*3m\\Work=45Nm\\Work=45J

7 0
2 years ago
Read 2 more answers
State the formula for calculating power
Alex
Where power<span> P is in watts, voltage V is in volts and current I is in amperes (DC).</span>Power Formula<span> 2 – Mechanical </span>power equation<span>: </span>Power<span> P = E ⁄ t where </span>power<span> P is in watts, </span>Power<span> P = work / time (W ⁄ t). Energy E is in joules, and time t is in seconds.</span>
7 0
3 years ago
If a rock is dropped from the top of a tower at the front of it and takes 3.6 seconds to hit the ground. Calculate the final vel
expeople1 [14]

Answer:

35.28m/s; 63.50m

Explanation:

<u>Given the following data;</u>

Time, t = 3.6 secs

Since it's a free fall, acceleration due to gravity = 9.8m/s²

Initial velocity, u = 0

To find the final velocity, we would use the first equation of motion;

V = u + at

Substituting into the equation, we have;

V = 0 + 9.8 * 3.6

V = 35.28m/s

Therefore, the final velocity of the penny is 35.28m/s.

To find the height, we would use the second equation of motion;

S = ut + \frac {1}{2}at^{2}

Substituting the values into the equation;

S = 0(3.6) + \frac {1}{2}*9.8*(3.6)^{2}

S = 0 + 4.9*12.86

S = 0.5 *36

S = 63.50m

Therefore, the height of the tower is 63.50m.

6 0
3 years ago
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