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SCORPION-xisa [38]
3 years ago
12

24 A person stands at the side of a straight railway track. A train moves towards the person and emits sound from its whistle. T

he person hears a sound of frequency 1690 Hz as the train approaches him. The person then hears sound of frequency 1500 Hz as the train moves away from him. The speed of sound in air is 340 m s–1. What is the speed of the train? A 20 m s–1 B 38 m s–1 C 41 m s–1 D 43 m s–
Physics
1 answer:
Andrei [34K]3 years ago
6 0
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A fatigue test was conducted in which the mean stress was 50 MPa (7250 psi) and the stress amplitude was 225 MPa (32,625 psi).
Tems11 [23]

Answer:

275 MPa, -175 MPa

-0.63636

450 MPa

Explanation:

\sigma_{max} = Maximum stress

\sigma_{min} = Minimum stress

\sigma_m = Mean stress = 50 MPa

\sigma_a = Stress amplitude = 225 MPa

Mean stress is given by

\sigma_m=\frac{\sigma_{max}+\sigma_{min}}{2}\\\Rightarrow \sigma_{max}+\sigma_{min}=2\sigma_m\\\Rightarrow \sigma_{max}+\sigma_{min}=2\times 50\\\Rightarrow \sigma_{max}+\sigma_{min}=100\ MPa\\\Rightarrow \sigma_{max}=100-\sigma_{min}

Stress amplitude is given by

\sigma_a=\frac{\sigma_{max}-\sigma_{min}}{2}\\\Rightarrow \sigma_{max}-\sigma_{min}=2\sigma_a\\\Rightarrow \sigma_{max}-\sigma_{min}=2\times 225\\\Rightarrow \sigma_{max}-\sigma_{min}=450\ MPa\\\Rightarrow 100-\sigma_{min}-\sigma_{min}=450\\\Rightarrow -2\sigma_{min}=350\\\Rightarrow \sigma_{min}=-175\ MPa

\sigma_{max}=100-\sigma_{min}\\\Rightarrow \sigma_{max}=100-(-175)\\\Rightarrow \sigma_{max}=275\ MPa

Maximum stress level is 275 MPa

Minimum stress level is -175 MPa

Stress ratio is given by

R=\frac{\sigma_{min}}{\sigma_{max}}\\\Rightarrow R=\frac{-175}{275}\\\Rightarrow R=-0.63636

The stress ratio is -0.63636

Stress range is given by

\sigma_{max}-\sigma_{min}=450\ MPa

Magnitude of the stress range is 450 MPa

8 0
3 years ago
Displacement vectors of 10 m west and 14 m west make a resultant vector that is _____.
Anastaziya [24]

For this case we can write each one of the vectors in the following way:

v1 = 10 i\\v2 = 14 i

This means that the x-axis is defined as positive towards the west.

Then, the resulting vector is:

v1 + v2 = 10i + 14i\\v1 + v2 = 24 i

Answer:

Displacement vectors of 10 m west and 14 m west make a resultant vector that is 24 m west

6 0
3 years ago
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The wave speed of sound waves traveling through four different media was measured at a constant temperature. Results are summari
Kitty [74]

Answer:b

Explanation:

6 0
3 years ago
. A grindstone increases in angular speed from 4.00 rad/s to 12.00 rad/s in 4.00 s. Through what angle does it turn during that
ZanzabumX [31]

Answer:

\theta=32rad

Explanation:

In an uniformly accelerated circular motion, the angle traveled by the object is given by:

\theta=\frac{\omega_f+\omega_0}{2}t

Here \omega_f is the final angular speed, \omega_0 is the initial angular speed and t is the time of the motion. Replacing the given values:

\theta=\frac{12\frac{rad}{s}+4\frac{rad}{s}}{2}(4s)\\\theta=32rad

5 0
3 years ago
You need eye drops for your dry eyes. You brought only a few dollars with you to the store. Which is the best method of choosing
Mnenie [13.5K]

Answer:

Compare brands first, but purchase the one that has lots of commercial advertisements, Compare ingredients and purchase the brand that is safe to use with soft contact lenses, Compare prices and purchase the most inexpensive brand.

Explanation:

4 0
3 years ago
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