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2 years ago

De ce omul nu poate suporta temperaturi mari intr-o atmosfera umeda?

Physics

2 answers:

Likurg_2 [28]2 years ago

7 0

Please ask in English

Galina-37 [17]2 years ago

3 0

Answer:

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Explanation:

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Starting from rest, a disk rotates about its central axis with constant angular acceleration. in 6.00 s, it rotates 44.5 rad. du

Klio2033 [76]

a. The disk starts at rest, so its angular displacement at time $t$ is

$\theta=\dfrac\alpha2t^2$

It rotates 44.5 rad in this time, so we have

$44.5\,\mathrm{rad}=\dfrac\alpha2(6.00\,\mathrm s)^2\implies\alpha=2.47\dfrac{\rm rad}{\mathrm s^2}$

b. Since acceleration is constant, the average angular velocity is

$\omega_{\rm avg}=\dfrac{\omega_f+\omega_i}2=\dfrac{\omega_f}2$

where $\omega_f$ is the angular velocity achieved after 6.00 s. The velocity of the disk at time $t$ is

$\omega=\alpha t$

so we have

$\omega_f=\left(2.47\dfrac{\rm rad}{\mathrm s^2}\right)(6.00\,\mathrm s)=14.8\dfrac{\rm rad}{\rm s}$

making the average velocity

$\omega_{\rm avg}=\dfrac{14.8\frac{\rm rad}{\rm s}}2=7.42\dfrac{\rm rad}{\rm s}$

Another way to find the average velocity is to compute it directly via

$\omega_{\rm avg}=\dfrac{\Delta\theta}{\Delta t}=\dfrac{44.5\,\rm rad}{6.00\,\rm s}=7.42\dfrac{\rm rad}{\rm s}$

c. We already found this using the first method in part (b),

$\omega=14.8\dfrac{\rm rad}{\rm s}$

d. We already know

$\theta=\dfrac\alpha2t^2$

so this is just a matter of plugging in $t=12.0\,\mathrm s$ . We get

$\theta=179\,\mathrm{rad}$

Or to make things slightly more interesting, we could have taken the end of the first 6.00 s interval to be the start of the next 6.00 s interval, so that

$\theta=44.5\,\mathrm{rad}+\left(14.8\dfrac{\rm rad}{\rm s}\right)t+\dfrac\alpha2t^2$

Then for $t=6.00\,\rm s$ we would get the same $\theta=179\,\rm rad$ .

7 0

3 years ago

Why are chemical changes considered “unseen”?

jeka57 [31]

<span>Because they occur at an atomic level, changing the actual structure of the thing.

</span>

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3 years ago

Read 2 more answers

A ruler of length 0.30m is pivoted at its centre. Equal and opposite forces of magnitude 2.0N are applied to the ends of the rul

kow [346]

Answer:

0.3858 Nm

Explanation:

The torque of the couple is the dot product of the force vector and the couple vector from 1 end of the ruler to the center. This equals to the product of their magnitude times the cosine() of the angle made by their direction:

$T = \vec{F} \cdot \vec{s} = Fscos(50^0) = 2 * 0.3 * 0.643 = 0.3858 Nm$

6 0

2 years ago

Can someone help me with these questions plz

Korolek [52]

Im not 100% on these but i can try

1. A compound is made up of elements and their different atoms

A. salt- compound (NaCl) is two elements Na (sodium) and Cl (chloride?)

B. Nitrogen- element its on the periodic table

C. Helium- element its on the periodic table

D. Water- compound (H2O) two elements hydrogen and oxygen

3. element, compound, compound, element

Hope this helps

8 0

3 years ago

How is electrolysis used in order to prevent materials from corrosion or rusting?

KengaRu [80]

Answer:

We use electrolysis to prevent a material from rusting,

The metal forms a coating around the material and hence prevents any contact between the material and the environment

This process also gives us the physical strength of the material and the aesthetic properties of the coated metal

the metal commonly used to coat the object is Zinc and the process is called galvanisation

6 0

3 years ago