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2 years ago

14

Based on The MOHS hardness Scale, which mineral could be scratched by a penny but not by a fingernail

1 answer:

melomori [17]2 years ago

6 0

The correct answer is B. Calcite

Explanation:

Mohs hardness scale indicates the hardness of minerals using a scale from 1 to 10 as well as defining the objects or tools that can be used to scratch the minerals. These two features of minerals are shown in the table of the image. About this, it is shown gypsum and talc can be scratched by just a fingernail, considering minerals with a hardness of 2.5 or below can be scratched by a fingernail. In the case of calcite that has a hardness of 3, this cannot be scratched by a fingernail, but it can be scratched by a penny, which works for minerals with a hardness of 3.5 or below. Thus, the correct answer is Calcite.

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A train moves from rest to a speed of 25 m/s in 30.0 seconds. What is the acceleration?

fredd [130]

Answer:

$a = 0.83\ m/s^2$

Explanation:

<u>Uniform Acceleration </u>

When an object changes its velocity at the same rate, the acceleration is constant.

The relation between the initial and final speeds is:

$v_f=v_o+a.t$

Where:

vf = Final speed

vo = Initial speed

a = Constant acceleration

t = Elapsed time

It's known a train moves from rest (vo=0) to a speed of vf=25 m/s in t=30 seconds. It's required to calculate the acceleration.

Solving for a:

$\displaystyle a=\frac{v_f-v_o}{t}$

Substituting:

$\displaystyle a=\frac{25-0}{30}$

$\boxed{a = 0.83\ m/s^2}$

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2 years ago

Electronics and inhabitants of the International Space Station generate a significant amount of thermal energy that the station

katrin2010 [14]

Answer:

4462.0927 W

Explanation:

$\epsilon$ = Emissivity of the panel = 1

$\sigma$ = Stefan-Boltzmann constant = $5.67\times 10^{-8}\ W/m^2K^4$

T = Temperature = (273.15+6)

Area of the panel is given by

$A=2\times 1.8\times 3.6\\\Rightarrow A=12.96\ m^2$

The power radiated is given by

$P=\epsilon \sigma AT^4\\\Rightarrow P=1\times 5.67\times 10^{-8}\times 12.96\times (273.15+6)^4\\\Rightarrow P=4462.0927\ W$

The power radiated from each panel is 4462.0927 W

5 0

3 years ago

The y-component of the force F which a person exerts on the handle of the box wrench is known to be 70 lb. Determine the x-compo

Yuri [45]

Answer:

<em>Fx = 121.24lb</em>

<em>F = 140lb</em>

Explanation:

Since we are not given the angles subtended by the force, we can assume it to be 30 degrees.

The y component of the force expressed by the formula:

Fy = Fsintheta

Given the y-component of the force F to bee 70lb

70lb = Fsintheta

Get magnitude of the force

F = 70/sin theta

F = 70/sin 30

F = 70/0.5

F = 140lb

Get the x-component of the force

Fx = Fcos theta

Fx = 140cos 30

Fx = 140(0.8660)

Fx = 1,212.4lb

<em>Hence the x-component of the force sis 121.24lb</em>

<em></em>

<em>Note that the angle used was assumed. Other values can as well be used</em>

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Naya [18.7K]

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2 years ago