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Lerok [7]
2 years ago
8

(8%) Problem 9: Helium is a very important element for both industrial and research applications. In its gas form it can be used

for welding, and since it has a very low melting point (only 0.95 K under 2.5 MPa) it can be used in liquid form to cool superconducting magnets, such as those found in particle physics experiments. Say we have a cylinder of n = 125 moles of Helium gas at room temperature (T = 20° C). The cylinder has a radius of r = 17 cm and a height h = 1.64 m.What pressure is Helium gas under?
Physics
1 answer:
exis [7]2 years ago
6 0

Answer:

2046.37 kPa

Explanation:

Given:

Number of moles, n = 125

Temperature, T = 20° C = 20 + 273 = 293 K

Radius of the cylinder, r = 17 cm = 0.17 m

Height of the cylinder, h = 1.64 m

thus,

volume of the cylinder, V = πr²h

= π × 0.17² × 1.64

= 0.148 m³

Now,

From the ideal gas law

we have

PV = nRT

here,

P is the pressure

R is the ideal gas constant = 8.314  J / mol. K

thus,

P × 0.148 = 125 × 8.314 × 293

or

P × 0.148 = 304500.25

or

P = 2046372.64 Pa = 2046.37 kPa

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A gas laser has a cavity length of 1/3 m and a single oscillation frequency of 9.0 x 1014 Hz. What is the cavity mode number?
Eddi Din [679]

Answer:

2 × 10⁶

Explanation:

Data provided in the question:

Cavity length, L = \frac{1}{3}m

Oscillation frequency, f_m = 9.0 × 10¹⁴ Hz

Now,

we know,

f_m=\frac{c}{\lambda_m}

here,

c is the speed of light = 3 × 10⁸ m/s

\lambda_m = Wavelength of mode m inside the laser cavity

m is the cavity mode number

Thus,

9.0\times10^{14}=\frac{3\times10^8}{\lambda_m}

or

\lambda_m = \frac{1}{3} × 10⁻⁶

Also,

m\lambda_m = 2L

Therefore,

m × \frac{1}{3} × 10⁻⁶ = 2 × \frac{1}{3}

or

m = 2 × 10⁶

5 0
2 years ago
When jumping, a flea reaches a takeoff speed of 1.0 m/s over a distance of 0.47 mm .What is the flea's acceleration during the j
garri49 [273]
We can use kinematics here if we assume a constant acceleration (not realistic, but they want a single value answer, so it's implied). We know final velocity, vf, is 1.0 m/s, and we cover a distance, d, of 0.47mm or 0.00047 m (1m = 1000mm for conversion). We also can assume that the flea's initial velocity, vi, is 0 at the beginning of its jump. Using the equation vf^2 = vi^2 + 2ad, we can solve for our acceleration, a. Like so: a = (vf^2 - vi^2)/2d = (1.0^2 - 0^2)/(2*0.00047) = 1,064 m/s^2, not bad for a flea!
8 0
2 years ago
Read 2 more answers
There is an electromagnetic wave traveling in the -z direction in a standard right-handed coordinate system. What is the directi
wlad13 [49]

Answer: The direction of the electric field, E→, is pointed in the +y direction.

Explanation:

One can use the right hand rule to illustrate the direction of travel of an electromagnetic and thereby get the directions of the electric field, magnetic field and direction of travel of the wave.

The right hand rule states that the direction of the thumb indicate the direction of travel of the electromagnetic wave (<em>in this case the -z direction</em>) and the curling of the fingers point in the direction of the magnetic field  B→ (<em>in this case the +x direction</em>), therefore, the electric field direction E→ is in the direction of the fingers which would be pointed towards the +y direction.

6 0
2 years ago
For some metal alloy, a true stress of 345 MPa (50040 psi) produces a plastic true strain of 0.02. How much will a specimen of t
Juliette [100K]

Answer:

24.348mm

Explanation:

NB: I'll be attaching pictures so as to depict missing mathematical expressions or special characters which are not easily found on keyboards

K = d / €^n

Note : d represents the greek alphabet epsilion.

K = 345 / 0.02⁰.²² = 816mPa

The true strain based upon the stress of 414mPa =

€= (€/k)^1/n = (414/816)¹/⁰.²² = 0.04576

However the true relationship between true strain and length is given by

€ = ln(Li/Lo)

Making Li the subject of formula by rearranging,

Li = Lo.e^€

Li = 520e⁰.⁰⁴⁵⁷⁶

Li = 544.348mm

The amount of elongation can be calculated from

Change in L = Li - Lo = 544.348 - 520 change in L = 24.348mm.

8 0
2 years ago
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oee [108]
The correct order is (in decreasing order of gravity strength)
Jupiter - Neptune - Venus - Mars

In fact, Wayne's weight on each planet is given by
W=mg
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8 0
2 years ago
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