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garri49 [273]
3 years ago
13

Edwin Hubble calculated the expansion rate of the universe. On what evidence did he base his calculation?

Physics
2 answers:
algol [13]3 years ago
7 0

Edwin Hubble calculated the expansion rate of the universe. The evidence that he base his calculation is the differences in redshift for galaxies. The answer is letter B. the red shift of galaxies was directly proportional to the distance of the galaxy from earth.  It means that bodies farther away from Earth were moving away faster. The Hubble’s constant is the ratio of distance to redshift equal to 170 kilometers per second per light year of distance.

Anni [7]3 years ago
7 0

Answer: B

Explanation:

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A 75.5 kg diver drops from a diving board 10.0 m above the waters surface. Find the divers speed just before he strikes the wate
jenyasd209 [6]

Answer:

<em>v=14 m/s</em>

Explanation:

<u>Mechanical Energy </u>

The kinetic energy of a body (K) is the capacity of doing work due to its speed. It can be expressed as

\displaystyle K=\frac{mv^2}{2}

The potential energy (U) is the capacity of doing work due to its height respect to a certain reference level.

U=mgh

The  mechanical energy is the sum of both

\displaystyle E_m=\frac{mv^2}{2}+mgh

The principle of conservation of mechanical energy states it must remain the same if no external force is acting on it. The diver drops from the diving board, which means its initial speed is zero (and so its initial kinetic energy). Thus, the mechanical energy at the jumping time is

\displaystyle E_m=mgh=(75)(10)(9.8)=7350\ J

When the diver is about to get into the water, his height reaches zero and the speed is at maximum. All the potential energy became kinetic energy, so

\displaystyle \frac{mv^2}{2}=7350\ J

Rearranging

\displaystyle v^2=\frac{2(7350)}{75}=196

v=\sqrt{196}=14\ m/s

The final speed of the diver is

\boxed{v=14\ m/s}

8 0
3 years ago
What is the resultant force acting on an object? The first force is 45 N West and the second is 23 N East.
Paul [167]

Answer:

22N West

Explanation:

45-23 because they are in opposite directions.

4 0
3 years ago
Your friends sit in a sled in the snow. If you apply a force pf 75 N to them, they have an acceleration of 0.9 m/s ^ 2. What is
Elza [17]

Answer:

Mass of the sled in the snow 83.33 kg.

<u>Explanation</u>:

Given that,  

Force applied to move the sled in the snow (F) = 75N

\text { Acceleration }(a)=0.9 \mathrm{m} / \mathrm{s}^{2}

We know that

Newton's second law of motion is  

\text { Force }=\text { mass } \times \text { acceleration }

F = ma (Or "force" is equal to "mass" times "acceleration".)

So if we move this around we can isolate mass and get mass

\text { Mass }=\frac{\text { force }}{\text { accelearation }}

\mathrm{M}=\frac{75}{0.9}

M = 83.33 kg

Mass of the sled in the snow <u>83.33 kg.</u>

3 0
3 years ago
Why did you spin counterclockwise rather than clockwise
rodikova [14]
<span>Because of the orbit of the earth and the sun and the moon. </span>
6 0
3 years ago
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On a cold winter day, a penny (mass 2.50 g) and a nickel (mass 5.00 g) are lying on the smooth (frictionless) surface of a froze
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