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3 years ago

The melting point of a substance occurs at the same temperatures as it’s blank point

Physics

2 answers:

azamat3 years ago

4 0

I think it's a.

Explanation:

melting point is boiling

Anna [14]3 years ago

3 0

I agree with them I belive I tea a as well

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A 39-foot ladder is leaning against a vertical wall. If the bottom of the ladder is being pulled away from the wall at the rate

Viefleur [7K]

Answer:

The rate of change of the area when the bottom of the ladder (denoted by $b$ ) is at 36 ft. from the wall is the following:

$\frac{dA}{dt}|_{b=36}=-571.2\, ft^2/s$

Explanation:

The Area of the triangle is given by $A=h\times b$ where $h=\sqrt{l^2-b^2}$ (by using the Pythagoras' Theorem) and $b$ is the length of the base of the triangle or the distance between the bottom of the ladder and the wall.

The area is then

$A=\sqrt{l^2-b^2}b$

The rate of change of the area is given by its time derivative

$\frac{dA}{dt}=\frac{d}{dt}\left(\sqrt{l^2-b^2}\cdot b\right)$

$\implies \frac{dA}{dt}=\frac{d}{dt}\left(\sqrt{l^2-b^2}\right)\cdot b+\frac{db}{dt}\cdot\sqrt{l^2-b^2}$

$\implies\frac{dA}{dt}=\frac{1}{2\sqrt{l^2-b^2}}\frac{d}{dt}(l^2-b^2)\cdot b+\sqrt{l^2-b^2}}\cdot \frac{db}{dt}$ Product rule

$\implies\frac{dA}{dt}=-\frac{1}{2\sqrt{l^2-b^2}}\cdot 2\cdot b^2\cdot \frac{db}{dt}+\sqrt{l^2-b^2}}\cdot \frac{db}{dt}$ Chain rule

$\implies\frac{dA}{dt}=-\frac{1}{\sqrt{l^2-b^2}}\cdot b^2\cdot \frac{db}{dt}+\sqrt{l^2-b^2}}\cdot \frac{db}{dt}$

$\implies\frac{dA}{dt}=\frac{db}{dt}\left(-\frac{1}{\sqrt{l^2-b^2}}\cdot b^2+\sqrt{l^2-b^2}}\right)$

In here we can identify $b=36\, ft$ , $l=39$ and $\frac{db}{dt}=8\,ft/s$ .

The result is then

$\frac{dA}{dt}=8\left(-\frac{1}{\sqrt{39^2-36^2}}\cdot 36^2+\sqrt{39^2-36^2}}\right)=-571.2\, ft^2/s$

3 0

3 years ago

When light travels through a small hole, it appears to be an observer that the light spreads out, blurring the outline of the ho

3241004551 [841]

Answer:

support lights as a wave

Explanation:

In the model of light as a particle, the experimenter would expect to see one small hole of light emerging on the wall. However, as the light spreads out, it behaves much like a wave that diffracts when going through a small hole.

7 0

3 years ago

A parallel plate capacitor filled with air with plate area 2-cm2 and plate separation of 0.5 mm is connected to a 12 V batter an

pashok25 [27]

Answer:

a) The charge of the capacitor is 4.25x10⁻¹¹C

b) The charge of the capacitor is 4.25x10⁻¹¹C because the battery is disconnected.

c) The potential difference across the plates is 18 V

d) The work is 7.64x10⁻¹⁰J

Explanation:

The capacitance of the capacitor is equal to:

$C=\frac{e_{0}A }{d}$

A = 2 cm² = 0.0002 m²

d = 0.5 mm = 0.0005 m

Replacing:

$C=\frac{8.85x10^{-12}*0.0002 }{0.0005} =3.54x10^{-12} F = 3.54pF$

a) The charge of the capacitor is equal to:

Q = C*V = 3.54 * 12 = 42.48 pC = 4.25x10⁻¹¹C

b) The charge is the same because the battery is disconnected (Q = 4.25x10⁻¹¹C)

c) If distance is increased, we have:

$C=\frac{8.85x10^{-12}*0.0002 }{0.00075} =2.36x10^{-12} F=2.36pF$

The potential is:

$V=\frac{Q}{C} =\frac{42.48}{2.36} =18V$

d) The work done is equal to:

$W=VQ=18*42.48=764.6pJ=7.64x10^{-10} J$

3 0

3 years ago

Read 2 more answers

The angle at which light hits a surface (angle of incidence) and the angle at which it is reflected away (angle of reflection) a

ira [324]

Answer:

are always the same

Explanation:

angle of incident is equal to the angle of reflection i = r

the normal is perpendicular to the reflecting surface

8 0

3 years ago

Whats the difference between bad conductors , insulators and dielectric

KatRina [158]

Insulators does not allow flow of electric charges at all.
bad conductors are those which can conduct electricity but offers more opposition (resistence) to the flow of current compared to the flow of current in a good conductor.
all dielectrics are insulators, but all insulators are not dielectric.

hope this help

6 0

3 years ago

Read 2 more answers