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3 years ago

One peice of evidence that the universe is expanding

1 answer:

3 0

Who Figured This Out? The American astronomer Edwin Hubble made the observations in 1925 and was the first to prove that the universe is expanding. He proved that there is a direct relationship between the speeds of distant galaxies and their distances from Earth. This is now known as Hubble's Law.

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Which statements describe acceleration? Check all that apply. Negative acceleration occurs when an object slows down in the posi

garik1379 [7]

Answer:

Negative acceleration occurs when the acceleration vector points to the left.

1. Object slowing down in the positive direction.

2. Object speeding up in the negative direction.

Following six statements:

1. T

2. F

3. T

4. T

5. F

6. T

Check direction of acceleration vector.

7 0

3 years ago

A helicopter starting on the ground is rising directly into the air at a rate of 25 ft/s. You are running on the ground starting

rusak2 [61]

Answer:

The rate of change of the distance between the helicopter and yourself (in ft/s) after 5 s is $\sqrt{725}$ ft/ sec

Explanation:

Given:

h(t) = 25 ft/sec

x(t) = 10 ft/ sec

h(5) = 25 ft/sec . 5 = 125 ft

x(5) = 10 ft/sec . 5 = 50 ft

Now we can calculate the distance between the person and the helicopter by using the Pythagorean theorem

$D(t) = \sqrt{h^2 + x^2}$

Lets find the derivative of distance with respect to time

$\frac{dD}{dt} (t) = \frac{2h \cdot \frac{dh}{dt} +2x \cdot\frac{dx}{dt}} {2\sqrt{h^2 + x^2}}$

Substituting the values of h(t) and x(t) and simplifying we get,

$\frac{dD}{dt}(t) = \frac{50t \cdot \frac{dh}{dt} + 20 \cdot \frac{dx}dt}{2\sqrt{625\cdot t^2 + 100 \cdot t^2}}$

$\frac{dh}{dt} = 25ft/sec$

$\frac{dx}{dt} = 10 ft/sec$

$\frac{Dd}{dt} (t) = \frac{1250t +200t}{2\sqrt{725}t}$ = $\frac{725}{\sqrt{725}}$ = $\sqrt{725}$ ft / sec

5 0

3 years ago

What is the density of a block of wood with a mass of 120 g and a volume of 200 cm

creativ13 [48]

D=m/V therefore the answer is 120/200 or 0.6

7 0

3 years ago

The peregrine falcon is the world's fastest known bird and has been clocked diving downward toward its prey at constant vertical

Sergio [31]

100m / 97.2m/s = 1.0288 seconds

7 0

3 years ago

Read 2 more answers

The table represents the speed of a car in a northern direction over several seconds. A 2-column table with 5 rows. The first co

Oksanka [162]

Answer:

Column 1 should be titled “Time,” and Column 2 should be titled

“Velocity.” ⇒ 1st answer

Explanation:

* Lets revise some definitions of graphs

A velocity-time graph represents the speed and direction an object

travels over a period of time.

Velocity-time graph is called speed-time graph.

The vertical axis of a velocity-time graph represents the velocity of the

object and horizontal axis represents the time from the initial position

In an acceleration time graph y-axis represents the acceleration, and

x-axis represents the time

The table represents the speed of a car in a northern direction over

several seconds

That means the data in the table represent the velocity of the car in a

certain time

Time (s) Velocity (m/s)

0 5

2 10

4 15

6 20

8 25

10 30

Column 1 would be on the x-axis

x-axis represents the time

Column 2 would be on the y-axis

y-axis represents the velocity

Column 1 should be titled “Time,” and Column 2 should be titled

“Velocity.”

3 0

4 years ago

Read 2 more answers