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3 years ago

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Which item is an example of a primary source? A. An academic paper analyzing John F. Kennedy's presidency B. A transcript of a p

residential speech C. A textbook about American foreign policy D. A newspaper article reflecting on the anniversary of the end of the Cold War

1 answer:

Viktor [21]3 years ago

7 0

A transcript of a presidential speech (APEX Class ;)

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Consider two copper wires of the same length. One has twice the cross-sectional area of the other. How do the resistances of the

JulsSmile [24]

Answer: a) when the cross section is doubled the resultant resistence is a half. This means the thicker wire have half resistence than the thinner wire.

Explanation: In order to explain this behaviur we have to consider the expresion for the resistence which is given by:

$R=\frac{\epsilon o L}{A}$ where L and A are the length and the cross section for the wire, respectively.

From this expresssion we can conclude the above, this means

R=εo*L/A if A is now 2A we have

R' = εo*L/2*A= R/2

6 0

3 years ago

Which of the following does not describe a scientific theory?

frez [133]

Explains how and why nature does<span> what it </span>does<span>. ... A </span>scientific<span> law is a statement based on repeated experimental observations that ...

</span>

4 0

4 years ago

What kind of front occurs when a cold air mass replaces a warm air mass?

Andreyy89

Answer:

Explained below:

Explanation:

When a cold air mass meets a warm air mass, a front is formed and if the cold air is replacing the warm air, it is known as a cold front. Cold fronts frequently cause thunderstorms or rain showers because they pressure the air in a steep upward direction at the front's edge. They are also responsible to bring the changes in atmospheric pressure and wind direction.

7 0

4 years ago

A slide whistle is an open-closed tube with an adjustable plunger that changes the length. You are playing the slide whistle and

Serjik [45]

Answer:

df / ft = -n 12 n= 1, 3, 5, ...

Explanation:

The speed of sound is

v = λ f

In a whistle that we approach by an open tube at one end and closed at the other, standing waves occur, which has a node in the closed part and a maximum in the open pate, whereby wavelength and the distance of the tube are related, the fundamental wave is

λ₁ = 4L

The harmonics are

λ₃ = 4L / 3

λ₅ = 4L / 5

The general formula

λₙ = 4L / n

with n = 1, 3, 5,…

We substitute and clear in the first equation

f = v n / 4L n = 1, 3, 5,…

Let's use derivatives to find the frequency change

df / dt = v n /4 dL⁻¹ / dt

d / dt (1/L) = - 1 / L² dL / dt

Where dL / dt = 8 cm / s

We replace

df / dt = - n v / L2 dL / dt

Let's calculate

df / dt = - n 340/152 8

df / ft = -n 12 n= 1, 3, 5, ...

4 0

4 years ago

A body accelerate uniformly from rest at the rate of 3meters per seconds for 8 sec . calculate the distance covered by the body

pishuonlain [190]

Answer:

96 m

Explanation:

Given:

v₀ = 0 m/s

a = 3 m/s²

t = 8 s

Find: Δx

Δx = v₀ t + ½ at²

Δx = (0 m/s) (8 s) + ½ (3 m/s²) (8 s)²

Δx = 96 m

3 0

3 years ago