All categories

3 years ago

Help i need step by step awnser

Physics

1 answer:

Murrr4er [49]3 years ago

5 0

Answer:

Gold

Silver

Mixture

Explanation:

Density

The density of an object of mass m and volume V is given by:

$\displaystyle d=\frac{m}{V}$

We are given the following densities:

Gold: 19.3 gr/cm3

Silver: 10.5 gr/cm3

With the data provided in the table, we can confirm which of the three columns corresponds to gold, silver, or a mix of both.

Calculating the first density: m1=1,930 gr, V1=100 cm3

$\displaystyle d1=\frac{m1}{V1}$

$\displaystyle d1=\frac{1,930}{100}$

$d1=19.3\ gr/cm^3$

This crown is made of gold

Calculating the second density: m2=1,930 gr, V2=184 cm3

$\displaystyle d2=\frac{m2}{V2}$

$\displaystyle d2=\frac{1,930}{184}$

$d2\approx 10.5\ gr/cm3$

This crown is made of silver

Calculating the last density: m3=1,930 gr, V3=150 cm3

$\displaystyle d3=\frac{m3}{V3}$

$\displaystyle d3=\frac{1,930}{150}$

$d3\approx 12.9 gr/cm^3$

Since the value of the density is between gold and silver, this crown is a mixture.

You might be interested in

If engine oil gets into the brake fluid, which of the following will happen? A. Rubber seals will swell. B. Everything should op

wlad13 [49]

The answers are A and D.

Engine oil reacts with rubber, changing its properties and causing it to expand. This will compromise rubber seals in the brake system and lead to a failure.

4 0

4 years ago

Read 2 more answers

Near the surface of Earth, an electric field points radially downward and has a magnitude of approximately 100 N/C. 1) What char

scoundrel [369]

Answer:

$-2.50\times10^{-4} \text{ C}$ or -0.000250 C

Explanation:

The field points downward, which is the direction of a positive charge. In order for the penny to rise, it has to have a negative charge since its direction is opposite that of the field.

To calculate the magnitude of the charge:

The penny is to accelerate upward so it must overcome gravity. Hence, the net force to cause it to accelerate it upward is the difference between the electrostatic force and its weight.

$F_N = F_E - W$

$F_E = F_N + W$

$F_E = ma + mg$

$F_E = m(a + g)$

$F_E = 0.0025(0.19+9.8)$

$F_E = 0.0025\times9.99$

Now, the electric field intensity is given by

$F_E = E \times q$

where q = charge

$q=\dfrac{F_E}{E}$

$q=\dfrac{0.0025\times9.99}{100}=0.00024975= 0.000250$ to 3 significant figures.

In standard form, q = $-2.50\times10^{-4} \text{ C}$ The negative sign indicates it has a negative charge, as explained initially.

5 0

3 years ago

On a speed-time graph, a horizontal line shows the change in speed is ____.

spayn [35]

On a speed/time graph, the height of the line at any point
shows the speed at that moment. If the line is horizontal,
then its height isn't changing, meaning that the speed isn't
changing. It's constant. The change is zero, until the line
starts rising or falling.

4 0

4 years ago

A mass of 150 g stretches a spring 1.568 cm. If the mass is set in motion from its equilibrium position with a downward velocity

nadezda [96]

Answer:

$u(t)=\frac{1}{5} sin\ (25t)$

Explanation:

Given:

mass of the body stretching the spring, $m=150\ g$

extension in spring, $\Delta x=1.568\ cm$

velocity of oscillation, $u'(0)=20\ cm.s^{-1}$

initial displacement position of equilibrium, $u(0)=0$

According to given:

$m.g=k.\Delta x$

$150\times 980=k\times 1.568$

$k=93750\ dyne.cm^{-1}$

we know frequency:

$\omega=\sqrt{\frac{k}{m} }$

$\omega=\sqrt{\frac{93750}{150} }$

$\omega=25$

Now, for position of mass in oscillation:

$u= A.sin\ (\omega.t)+B.cos\ (\omega.t)$

$u= A.sin\ (25.t)+B.cos\ (25.t)$

at $t=0;\ u(0)=0\ \Rightarrow A=0$

∴ $u(t)=B.sin\ (25.t)$

∵ at $t=0;\ u'(0)=20\ cm.s^{-1}\ \Rightarrow B=\frac{1}{5}$

$u(t)=\frac{1}{5} sin\ (25t)$

7 0

3 years ago

A horizontal disk rotates about a vertical axis through its center. Point P is midway between the center and the rim of the disk

rjkz [21]

If the disk turns with constant angular velocity, the following statements about it are true

The linear acceleration of Q is twice as great as the linear acceleration of P
is moving twice Q as fast as P.

Answer: Options D and E

Explanation:

Let us consider that R is the radius of the circular disc. So as Q is on the rim, so the distance of Q from the centre of the disc is R and as P is the midpoint between centre and rim of the disk, so the distance of P from the centre is R/2.

As we know that the angular velocity of the circular disk will be equal to the ratio of distance covered by that point to the time taken. So the angular velocity at point Q will be

$\text { Angular velocity at point } Q=\frac{\text { Distance covered by point } Q}{\text { Time }}=\frac{2 \pi R}{T}=v$

As R is the distance of point Q from the centre of the disc.

Similarly ,

$\text { Angular velocity at point } P=\frac{\text { Distance covered by point } P}{\text { Time }}=\frac{2 \pi\left(\frac{\mathrm{R}}{2}\right)}{T}=\frac{\pi R}{T}=v^{\prime}$

So if we equate v with v’ we obtain that

$v=2 v^{\prime}$

Therefore, the point Q will be moving twice as fast as P. As the velocity of Q is more than O, the linear acceleration of point Q will also be twice as great as the linear acceleration of P.

This is because acceleration is directly proportional to the rate of change in velocity. So if velocity increases in the factor of 2, the acceleration of point Q will also increase twice with respect to point P.

5 0

4 years ago

Help i need step by step awnser​

Help i need step by step awnser