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stiv31 [10]
2 years ago
9

To understand thermal linear expansion in solid materials. Most materials expand when their temperatures increase. Such thermal

expansion, which is explained by the increase in the average distance between the constituent molecules, plays an important role in engineering. In fact, as the temperature increases or decreases, the changes in the dimensions of various parts of bridges, machines, etc., may be significant enough to cause trouble if not taken into account. That is why power lines are always sagging and parts of metal bridges fit loosely together, allowing for some movement. It turns out that for relatively small changes in temperature, the linear dimensions change in direct proportion to the temperature.
For instance, if a rod has length L0 at a certain temperature T0 and length L at a higher temperature T, then the change in length of the rod is proportional to the change in temperature and to the initial length of the rod: L - L0 = αL0(T - T0),
or
ΔL = αL0ΔT.
Here, α is a constant called the coefficient of linear expansion; its value depends on the material. A large value of α means that the material expands substantially as the temperature increases; smaller values of α indicate that the material tends to retain its dimensions. For instance, quartz does not expand much; aluminum expands a lot. The value of α for aluminum is about 60 times that of quartz!
Questions:
A) Compared to its length in the spring, by what amount ΔLwinter does the length of the bridge decrease during the Teharian winter when the temperature hovers around -150°C?
B) Compared to its length in the spring, by what amount ΔLsummer does the length of the bridge increase during the Teharian summer when the temperature hovers around 700°C?

Physics
1 answer:
Marat540 [252]2 years ago
5 0

Answer:

Check the explanation

Explanation:

Kindly check the attached image below to see the step by step explanation to the question above.

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konstantin123 [22]

Answer:

Cardiac Arrest, burns, and nerve damage.

Explanation:

Basically, the main risk is cardiac arrest, caused by the electric current interfering with the normal operation of the heart muscle. Other possible damages are burns due to the electric energy vaporizing the water inside the cells, and nerve damage caused by excessive current through the nerves.

7 0
2 years ago
Where is the near point of an normal eye when accidentally wear a contact lens with a power of +2.0 diopters?
Lerok [7]

Answer:

The near point of an eye with power of +2 dopters, u' = - 50 cm

Given:

Power of a contact lens, P = +2.0 diopters

Solution:

To calculate the near point, we need to find the focal length of the lens which is given by:

Power, P = \frac{1}{f}

where

f = focal length

Thus

f = \frac{1}{P}

f = \frac{1}{2} = + 0.5 m

The near point of the eye is the point distant such that the image formed at this point can be seen clearly by the eye.

Now, by using lens maker formula:

\frac{1}{f} = \frac{1}{u} + \frac{1}{u'}

where

u = object distance = 25 cm = 0.25 m = near point of a normal eye

u' = image distance

Now,

\frac{1}{u'} = \frac{1}{f} - \frac{1}{u}

\frac{1}{u'} = \frac{1}{0.5} - \frac{1}{0.25}

\frac{1}{u'} = \frac{1}{f} - \frac{1}{u}

Solving the above eqn, we get:

u' = - 0.5 m = - 50 cm

7 0
2 years ago
You are on a train that is traveling at 3.0 m/s along a level straight track. Very near and parallel to the track is a wall that
loris [4]

Questions Diagram is attached below

Answer:

T=2.08s

Explanation:

From the question we are told that:

Speed of Train V=3.0m.s

Angle \theta=12\textdegree

Height of window h_w=0.90m

Width of window w_w=2.0m

The Horizontal distance between B and A from Trigonometric Laws is mathematically given by

 b=\frac{0.9}{tan12}

 b=4.23

Therefore

Distance from A-A

 d_a=2.0+4.23

 d_a=6.23

Therefore

Time Required to travel trough d is mathematically given as

 T=\frac{d_a}{v}

 T=\frac{6.23}{3}

 T=2.08s

5 0
2 years ago
-A pool ball leaves a 0.70 meter high table with an initial velocity of 2.4 m/s. Predict the time required for the pool ball to
lorasvet [3.4K]

Answer:

0.70+2.4=23.7+35.0=answer

Explanation:

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