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3 years ago

Chemical reactions and nuclear reactions cause matter to change in different

Physics

2 answers:

musickatia [10]3 years ago

7 0

Answer:

B. Atoms and their electrons are rearranged.

D. The elements stay the same.

STatiana [176]3 years ago

6 0

Answer:

Physical changes only change the appearance of a substance, not its chemical composition. Chemical changes cause a substance to change into an entirely substance with a new chemical formula. Chemical changes are also known as chemical reactions.

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How does the scattering of tiny particles in the air affect the colors of the sky at sunrise and sunset

timofeeve [1]

It affects the colors of the sky at sunrise and sunset because only the longer-wavelengths colors are visible.

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4 years ago

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A train travels 600 km in one hour. What is the trains velocity in meters/second

eimsori [14]

v= s/t

600 ÷ 60

10 m/s

4 0

4 years ago

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What is the force per unit area at this point acting normal to the surface with unit nor- Side View √√ mal vector n = (1/ 2)ex +

Mumz [18]

Complete Question:

Given $\sigma = \left[\begin{array}{ccc}10&12&13\\12&11&15\\13&15&20\end{array}\right]$ at a point. What is the force per unit area at this point acting normal to the surface with $\b n = (1/ \sqrt{2} ) \b e_x + (1/ \sqrt{2}) \b e_z$ ? Are there any shear stresses acting on this surface?

Answer:

Force per unit area, $\sigma_n = 28 MPa$

There are shear stresses acting on the surface since $\tau \neq 0$

Explanation:

$\sigma = \left[\begin{array}{ccc}10&12&13\\12&11&15\\13&15&20\end{array}\right]$

equation of the normal, $\b n = (1/ \sqrt{2} ) \b e_x + (1/ \sqrt{2}) \b e_z$

$\b n = \left[\begin{array}{ccc}\frac{1}{\sqrt{2} }\\0\\\frac{1}{\sqrt{2} }\end{array}\right]$

Traction vector on n, $T_n = \sigma \b n$

$T_n = \left[\begin{array}{ccc}10&12&13\\12&11&15\\13&15&20\end{array}\right] \left[\begin{array}{ccc}\frac{1}{\sqrt{2} }\\0\\\frac{1}{\sqrt{2} }\end{array}\right]$

$T_n = \left[\begin{array}{ccc}\frac{23}{\sqrt{2} }\\0\\\frac{27}{\sqrt{33} }\end{array}\right]$

$T_n = \frac{23}{\sqrt{2} } \b e_x + \frac{27}{\sqrt{2} } \b e_y + \frac{33}{\sqrt{2} } \b e_z$

To get the Force per unit area acting normal to the surface, find the dot product of the traction vector and the normal.

$\sigma_n = T_n . \b n$

$\sigma \b n = (\frac{23}{\sqrt{2} } \b e_x + \frac{27}{\sqrt{2} } \b e_y + \frac{33}{\sqrt{2} } \b e_z) . ((1/ \sqrt{2} ) \b e_x + 0 \b e_y +(1/ \sqrt{2}) \b e_z)\\\\\sigma \b n = 28 MPa$

If the shear stress, $\tau$ , is calculated and it is not equal to zero, this means there are shear stresses.

$\tau = T_n - \sigma_n \b n$

$\tau = [\frac{23}{\sqrt{2} } \b e_x + \frac{27}{\sqrt{2} } \b e_y + \frac{33}{\sqrt{2} } \b e_z] - 28( (1/ \sqrt{2} ) \b e_x + (1/ \sqrt{2}) \b e_z)\\\\\tau = [\frac{23}{\sqrt{2} } \b e_x + \frac{27}{\sqrt{2} } \b e_y + \frac{33}{\sqrt{2} } \b e_z] - [ (28/ \sqrt{2} ) \b e_x + (28/ \sqrt{2}) \b e_z]\\\\\tau = \frac{-5}{\sqrt{2} } \b e_x + \frac{27}{\sqrt{2} } \b e_y + \frac{5}{\sqrt{2} } \b e_z$

$\tau = \sqrt{(-5/\sqrt{2})^2 + (27/\sqrt{2})^2 + (5/\sqrt{2})^2} \\\\ \tau = 19.74 MPa$

Since $\tau \neq 0$ , there are shear stresses acting on the surface.

3 0

3 years ago

A 60-kg skate boarder is standing on his stationary board. A bigger, out of control 75-kg skate boarder crashes into him with a

andrezito [222]

Answer:

2.22m/s

Explanation:

Given parameters:

M1 = 60kg

M2 = 75kg

V1 = 0m/s

V2 = 4m/s

Unknown;

Velocity after collision = ?

Solution:

To solve this problem, we must understand that the momentum before and after collision of the bodies must be the same;

M1 V1 + M2 V2 = v(M1 + M2)

So;

60 x 0 + 75 x 4 = v (60 +75)

300 = 135v

v = 2.22m/s

3 0

3 years ago

The last main subatomic particle to be discovered was the _____.

kati45 [8]

<span>The last main subatomic particle to be discovered was the antihelium-4. It was discovered on 2011 and it is measured and produces through the STAR detector. The Antihelium-4 was discovered accidentally when an experiment was conducted. It is also the first particle that was discovered by the means of experiment.</span>

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3 years ago