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3 years ago

Why are metals sometimes added to gold?

Physics

2 answers:

MrRa [10]3 years ago

8 0

Answer: In order for the mixture of gold and added metals to become hard and suitable for processing.

Explanation: Gold is precious metal, it has a great value, and it used to serve as a means of payment, but also proof of wealth, status and power. Gold as such is soft, and in order to improve hardness it is mixed with another metal, such as nickel, copper, palladium, zinc, etc. For example, white gold is obtained with a mixture of pure gold and nickel, which gives the mixture a white color, and is sufficiently tough suitable for making rings. Based on the composition of the mixture that is the percentage of gold in the mixture, the number of karats is determined, which also means the value of gold itself. For example, the 999 gold has 99.9% of the gold in the mixture, which means 24 K (karats), and represents the so-called mixture with the most valuable percentage of gold, or the purest of which can be purchased.

Komok [63]3 years ago

7 0

Because solo gold isn't strong material. But with admixture it's stronger.

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Why are strokes and Alzheimer's disease serious conditions? Select all that apply. You can die from either one.

Sladkaya [172]

The first and fourth option my dudette
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3 years ago

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The spring of a toy car stores 10 J of potential energy. Only 8 J of energy changes to kinetic energy as the car moves. What hap

son4ous [18]

Answer:

It has been converted into thermal energy due to friction

Explanation:

According to the law of conservation of energy, energy cannot be created nor destroyed, but only transformed from one form into another.

Applied to this problem, it means that the total initial energy of the spring-toy system must be conserved.

Therefore:

- At the beginning, the total energy stored in the spring is 10 J

- After the toy is released, the total energy must still be 10 J.

In reality, we are told that the kinetic energy of the car is only 8 J. The other 2 J have not been destroyed, but they have been converted into thermal energy, due to the presence of frictional forces that act against the motion of the toy car.

3 0

3 years ago

Birdman is flying horizontally at a

den301095 [7]

Answer:

68 m

Explanation:

Given that the horizontal velocity of the birdman = 17 m/s and

the height, h= 78 m.

The gravitational force is acting in the downward direction, so it will not change the horizontal speed.

The horizontal speed will remains be constant and will be equal to the initial horizontal speed of the turd.

Initially, the turd was also flying horizontally with the birdman, so the initial velocity of the turd is the same as the horizontal velocity of the birdman, i.e In the horizontal direction, $u_0=17$ m/s.

In the vertical direction, u = 0,

The distance to be traveled, in the direction of application of force, is equals to the height of the turd, i.e

s= 78 m

Let t be the time taken to cover a distance of 78 m.

Now, applying the equation of motion in the vertical direction,

$s=ut+\frac 12 at^2$

where u is the initial velocity and a is the acceleration due to gravity in the direction of displacement,s.

Here, $a=g=9.81 m/s^2$ , so

$78=0\times t +\frac 12 (9.81)t^2$

$\Rightarrow t^2=(78\times2)/9.81$

$\Rightarrow t = 4$ seconds.

Hence, the time taken to reach the ground is 4 seconds.

As the horizontal speed, $u_0=17$ m/s, is constant throughout the journey, so

the horizontal distance covered by turd

$= u\times t$

$= 17 \times 4 = 68$ m.

So, the distance of landing from the start of the field is 68 m as the birdman releases a turd directly above the start of the field.

Hence, the robot must hold the bucket at a distance of 68 m from the start of the field.

5 0

3 years ago

What is meant by the statement,the linear expansivity of copper is 0.000017k

Aliun [14]

Answer:

The change in length per unit length per degree rise in temperature of copper is 0.000017k

Explanation:

Given that :

The linear expansivity of copper is 0.000017k. This simply means that ; for a given copper length, the length of such copper will increase by 0.000017k for every degree rose in temperature of the copper rod.

Therefore, the change in length per unit length per degree rise in temperature (k) is 0.000017

4 0

3 years ago

Tarik winds a small paper tube uniformly with 183 turns 183 turns of thin wire to form a solenoid. The tube's diameter is 9.49 m

Rufina [12.5K]

<h2>Answer:</h2>

143μH

<h2>Explanation:</h2>

The inductance (L) of a coil wire (e.g solenoid) is given by;

L = μ₀N²A / l --------------(i)

Where;

l = the length of the solenoid

A = cross-sectional area of the solenoid

N= number of turns of the solenoid

μ₀ = permeability of free space = 4π x 10⁻⁷ N/A²

<em>From the question;</em>

N = 183 turns

l = 2.09cm = 0.0209m

diameter, d = 9.49mm = 0.00949m

A = π d² / 4 [Take π = 3.142 and substitute d = 0.00949m]

A = 3.142 x 0.00949² / 4

A = 7.1 x 10⁻⁵m²

<em>Substitute these values into equation (i) as follows;</em>

L = 4π x 10⁻⁷ x 183² x 7.1 x 10⁻⁵ / 0.0209 [Take π = 3.142]

L = 4(3.142) x 10⁻⁷ x 183² x 7.1 x 10⁻⁵ / 0.0209

L = 143 x 10⁻⁶ H

L = 143 μH

Therefore the inductance in microhenrys of the Tarik's solenoid is 143

6 0

3 years ago