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3 years ago

4. What determines which goods a country should produce and export?

Physics

1 answer:

tangare [24]3 years ago

8 0

Answer:

net exporter

Explanation:

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Determine the amount of time for polonium-210 to decay to one fourth its original quantity. The half-life of polonium-210 is 138

ira [324]

Answer: 276 days

Explanation:

This problem can be solved using the Radioactive Half Life Formula:

$A=A_{o}.2^{\frac{-t}{h}}$ (1)

Where:

$A=\frac{1}{4}A_{o}$ is the final amount of the material

$A_{o}$ is the initial amount of the material

$t$ is the time elapsed

$h=138 days$ is the half life of polonium-210

Knowing this, let's substitute the values and find $t$ from (1):

$\frac{1}{4}A_{o}=A_{o}2^{\frac{-t}{138 days}}$ (2)

$\frac{A_{o}}{4A_{o}}=2^{\frac{-t}{138 days}}$ (3)

$\frac{1}{4}=2^{\frac{-t}{138 days}}$ (4)

Applying natural logarithm in both sides:

$ln(\frac{1}{4})=ln(2^{\frac{-t}{138 days}})$ (5)

$-1.386=-\frac{t}{138days}ln(2)$ (6)

Clearing $t$ :

$t=276days$ (7)

7 0

3 years ago

A diffraction grating with 140 slits per centimeter is used to measure the wavelengths emitted by hydrogen gas. At what angles i

Degger [83]

Answer:

0.003181 radians

0.003005 radians

Explanation:

Number of slits = 140 /cm

λ = Wavelength = 434 nm = 434×10⁻⁹ m

m = 3 Third order spectrum

Space between slits

$d=\frac{0.01}{140} =7.14\times 10^{-5}\ m$

Now,

$dsin\theta = m\lambda\\\Rightarrow \theta=sin^{-1}\left(\frac{m\lambda}{d}\right)\\\Rightarrow \theta=sin^{-1}\left(\frac{3\times 434\times 10^{-9}}{7.14\times 10^{-5}}\right)\\\Rightarrow \theta=sin^{-1}0.018228\\\Rightarrow \theta=0.01823^{\circ}=0.01823\times \frac{\pi}{180}=0.003181 radians$

0.003181 radians

When λ = 410 nm = 410×10⁻⁹ m

$dsin\theta = m\lambda\\\Rightarrow \theta=sin^{-1}\left(\frac{m\lambda}{d}\right)\\\Rightarrow \theta=sin^{-1}\left(\frac{3\times 410\times 10^{-9}}{7.14\times 10^{-5}}\right)\\\Rightarrow \theta=sin^{-1}0.01722\\\Rightarrow \theta=0.01722^{\circ}=0.01722\times \frac{\pi}{180}=0.003005 radians$

0.003005 radians

5 0

4 years ago

A 1.2 kg block is held at rest against the spring with a force constant k= 730 N/m. Initially, the spring is compressed a distan

Nesterboy [21]

Answer:

Compression distance: $d \approx 0.102\,m$

Explanation:

According to this statement, we know that system is non-conservative due to the rough patch. By Principle of Energy Conservation and Work-Energy Theorem, we have the following expression that represents the system having a translational kinetic energy ( $K$ ), in joules, at the expense of elastic potential energy ( $U$ ), in joules, and overcoming work losses due to friction ( $W_{l}$ ), in joules:

$K + W_{l} = U$ (1)

By definitions of translational kinetic and elastic potential energies and work losses due to friction, we expand the equation described above:

$\frac{1}{2}\cdot m \cdot v^{2} +\mu\cdot m\cdot g \cdot s = \frac{1}{2} \cdot k \cdot d^{2}$ (2)

Where:

$m$ - Mass of the block, in kilograms.

$v$ - Final velocity of the block, in meters per second.

$\mu$ - KInetic coefficient of friction, no unit.

$g$ - Gravitational acceleration, in meters per square second.

$s$ - Width of the rough patch, in meters.

$k$ - Spring constant, in newtons per meter.

$d$ - Compression distance, in meters.

If we know that $m = 1.2\,kg$ , $v = 2.3\,\frac{m}{s}$ , $\mu = 0.44$ , $g = 9.807\,\frac{m}{s^{2}}$ , $s = 0.05\,m$ and $k = 730\,\frac{N}{m}$ , then the compression distance of the spring is:

$\frac{1}{2}\cdot m \cdot v^{2} +\mu\cdot m\cdot g \cdot s = \frac{1}{2} \cdot k \cdot d^{2}$

$m\cdot v^{2} + 2\cdot m\cdot g \cdot s = k\cdot d^{2}$

$d = \sqrt{\frac{m\cdot (v^{2}+2\cdot g\cdot s)}{k} }$

$d \approx 0.102\,m$

4 0

3 years ago

Sound travels 2146 m through a material in 1.4 seconds. What is the material?

Sonbull [250]

Your basically breaking the sound beerier <span />

5 0

3 years ago

A material that can be represented by a chemical formula is a ___

DedPeter [7]

Compound or a simple element.

For example O2 is a chemical formula and represents the element oxigen, because it exists as a diatomic molecule in the air.

NaCl is a chemical formula and represents sodium chloride

CH4 is a chemical formula and represents methane.

3 0

3 years ago