. 1. True False In AM waves, amplitude changes.

Water being put in a freezer will go through what phase change?

Nana76 [90]

Explanation:

If water is being put in fridge it will get freezed.

3 0

3 years ago

În ce raport de mase trebuie amestecate două cantități din același lichid, având temperaturile t1=10 grade Celsius, respectiv t2

Brilliant_brown [7]

Răspuns:

7: 4

Explicaţie:

Formula pentru calcularea cantității de căldură absorbită este exprimată ca;

Q = mc∆t

m este masa substanței

c este capacitatea termică specifică

∆t este schimbarea temperaturii

Conform legii calorimetriei, căldura pierdută de substanța rece = căldura câștigată de substanța fierbinte.

Folosind formula

(mc∆t) rece = (mc∆t) fierbinte

McCw∆tc = MhCw∆th

Deoarece au aceeași capacitate de căldură specifică, se vor anula. Ecuația devine;

Mc∆tc = Mh∆th ...... 1

Pentru apa rece;

∆tc = 45 ° C - 10 ° C

∆tc = 35 ° C

Pentru apa fierbinte:

∆th = 65 ° C - 45 ° C

∆th = 20 ° C

Înlocuiți în ecuația 1;

Mc (35) = Mh (20)

35Mc = 20Mh

Luând raportul dintre masa apei reci și cea fierbinte:

Mh / Mc = 35/20

Mh / Mc = 7/4

Prin urmare, lichidul trebuie amestecat împreună în raportul 7: 4

8 0

3 years ago

When the volcano Krakatoa erupted in 1883, it was heard 5000 km away. Which statement about the sound from the volcano is not co

lina2011 [118]

Answer a) is incorrect as sound does not travel in a vacuum.

7 0

3 years ago

Students in an introductory physics lab are performing an experiment with a parallel-plate capacitor made of two circular alumin

Zarrin [17]

Answer:

$\rm 9.186\times 10^{-7}\ C.$

Explanation:

Given:

Diameter of the plates of the capacitor, D = 21 cm = 0.21 m.
Distance of separation between the plates, d = 1.0 cm = 0.01 m.
Minimum value of electric field that produces spark, $\rm E=3\times 10^6\ N/C.$

When the dimensions of the plate of the capacitor is comparatively much larger than the distance of separation between the plates, then, according to the Gauss' law of electrostatics, the value of the electric field strength in the region between the plates of the capacitor is given by

$\rm E=\dfrac{\sigma}{\epsilon_o}.$

where,

$\rm \sigma$ = surface charge density of the plate of the capacitor = $\dfrac qA$ .

$\rm q$ = magnitude of the charge on each of the plate.
$\rm A$ = surface area of each of the plate = $\rm \pi \times (Radius)^2=\pi \times\left ( \dfrac{D}{2}\right )^2= \pi \times \left ( \dfrac{0.21}{2}\right )^2=3.46\times 10^{-2}\ m^2.$
$\epsilon_o$ = electrical permittivity of free space, having value = $8.85\times 10^{-12}\rm \ C^2N^{-1}m^{-2}.$

For the minimum value of electric field that produces spark,

$\rm E = \dfrac{q}{A\epsilon_o}\\\Rightarrow q = E\ A\epsilon_o\\=3\times 10^6\times 3.46\times 10^{-2}\times 8.85\times 10^{-12}\\=9.186\times 10^{-7}\ C.$