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3 years ago

Gold-leaf electroscope uses

1 answer:

7 0

-identifies an electric charge
-it can identify its polarity (positive or negative) if you compare it to a charge that you already know
-can identify the magnitude of a charge (how big of a charge it is)

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A child is riding a merry-go-round that is turning at 7.18 rpm. If the child is standing 4.65 m from the center of the merry-go-

iVinArrow [24]

Answer:

B) 3.50 m/s

Explanation:

The linear velocity in a circular motion is defined as:

$v=\omega r(1)$

The angular frequency ( $\omega$ ) is defined as 2π times the frequency and r is the radius, that is, the distance from the center of the circular motion.

$\omega=2\pi f(2)$

Replacing (2) in (1):

$v=2\pi fr$

We have to convert the frequency to Hz:

$7.18rpm*\frac{1Hz}{60rpm}=0.12Hz$

Finally, we calculate how fast is the child moving:

$v=2\pi(0.12Hz)(4.65m)\\v=3.5\frac{m}{s}$

3 0

3 years ago

calculate the time rate of change in air density during expiration. Assume that the lung has a total volume of 6000mL, the diame

kipiarov [429]

Answer:

The time rate of change in air density during expiration is 0.01003kg/m³-s

Explanation:

Given that,

Lung total capacity V = 6000mL = 6 × 10⁻³m³

Air density p = 1.225kg/m³

diameter of the trachea is 18mm = 0.018m

Velocity v = 20cm/s = 0.20m/s

dv /dt = -100mL/s (volume rate decrease)

= 10⁻⁴m³/s

Area for trachea =

$\frac{\pi }{4} d^2\\= 0.785\times 0.018^2\\= 2.5434 \times10^-^4m^2$

0 - p × Area for trachea =

$\frac{d}{dt} (pv)=v\frac{ds}{dt} + p\frac{dv}{dt}$

$-1.225\times2.5434\times10^-^4\times0.20=6\times10^-^3\frac{ds}{dt} +1.225(-1\times10^-^4)$

⇒ $-0.623133\times10^-^4+1.225\times10^-^4=6\times10^-^3\frac{ds}{dt}$

$\frac{ds}{dt} = \frac{0.6018\times10^-^4}{6\times10^-^3} \\\\= 0.01003kg/m^3-s$

ds/dt = 0.01003kg/m³-s

Thus, the time rate of change in air density during expiration is 0.01003kg/m³-s

3 0

3 years ago

Read 2 more answers

"The greater the height of an object, the *BLANK* its gravitational potential energy."

-Dominant- [34]

Answer:

the greater the height of an object the *greater* its gravitational potential energy

greater

3 0

2 years ago

Read 2 more answers

What does a light bulb marked 100 W mean? (A) Uses 100 A of energy per second. (B) Uses 100 J of current per second. (C) 100 C o

Mandarinka [93]

Answer:

(E) none of these.

Explanation:

first that all we need the meaning of a Watt

" is a unit of power. In the International System of Units (SI) it is defined as a derived unit of 1 joule per second,[1] and is used to quantify the rate of energy transfer."

definition taken from wikipedia.org

now with this concept we have that:

100 W means 100 J/s .Therefore it uses 100 J energy per second

therefore on the answers don't mention this three terms together

Joules, energy and second so the answer must be.

(E) None of these

3 0

3 years ago

The chemical formula for two substances are Fe and Fe2O3 which is an element and which is a compound how would you justify the s

ipn [44]

Answer:

Fe - Element

Fe2O3 - Compound

Explanation:

From the given chemical formula for two substances, Fe and Fe2O3, Fe is an element while fe2O3 is a compound.

It is so because an element is consist of the same type of atoms while a compund is consist of different atoms under specific proportions. for example: Fe is an element while fe2O3 is a compound.

Hence, the correct answer is:

Fe - Element

Fe2O3 - Compound

8 0

3 years ago