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madreJ [45]
3 years ago
12

Which type of matter is gold an element used in making jewelry A.) A heterogeneous mixture B.) A pure substance C.) A crystallin

e compound D.) A homogeneous mixture
Physics
2 answers:
Mnenie [13.5K]3 years ago
7 0

Answer:

A

Explanation:

<em>The gold used in the making of jewelry is usually not pure but a heterogeneous mixture of metals. Pure gold is quite soft and even though it may look better in appearance compared to those made using heterogeneous mixtures, it usually bends easily. Hence, in order to make the jewelry more durable, gold is usually mixed with other metals to form a heterogeneous mixture. </em>

The correct option is A.

DaniilM [7]3 years ago
4 0

Answer:

BBBBBBBBB

Explanation:

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A block (mass = 61.2 kg) is hanging from a massless cord that is wrapped around a pulley (moment of inertia = 1/2MR2 kg · m2, wh
kolezko [41]

Answer:

The angular velocity is  w = 53.35 \ rounds /minute

Explanation:

From the question we are told that

    The mass of the block is  m = 61.2kg

     The of the pulley is  M = 14.2 kg

      The radius of the pulley is  R = 1.5m

       The radius  of the cord around the pulley is  r = 1.5 m

       The distance of the block to the floor is  d = 8.0 m

         

From the question we are told that the moment of inertia of the pulley is

          I  = \frac{1}{2} MR^2 kg \cdot m^2

Substituting value  

         I = \frac{1}{2}  * 14.2 * (1.5)^2

         I = 15.975 kg \cdot m^2

Using the Newtons law we can express the force acting on the vertical axis as

              ma = mg -T

         =>  T = mg -ma

Now when the pulley is rotated that  torque generated on the massless cord as a r result of the tension T and the radius of the cord around the pulley is mathematically represented as

                  \tau = I \alpha

     Here \alpha is the angular acceleration

           Here \tau is the torque which can be equivalent to

              \tau = T r

  Substituting this above

            Tr = I \alpha      

Substituting for T

         (mg - ma ) r =  I\  r \alpha

Here a is the  linear acceleration which is mathematically represented as

           a = r\alpha

    (mg - m(r\alpha ) ) r =  I\  r \alpha

     mgr = I\alpha  + m(r\alpha ) r

    mgr = \alpha  [ I + mr^2]

   making \alpha the subject

          \alpha  = \frac{mgr}{I -mr ^2}          

   Substituting values

            \alpha  = \frac{61.2 * 1.5 * 9.8}{15.975 + (61.2 ) * (1.5)^2}

             \alpha =5.854 rad /s^2

Now substituting into the equation above to obtain the acceleration

             a = 5.854 * 1.5

                a=8.78 m/s^2

This acceleration is a = \frac{v}{t}

and v is the linear velocity with is mathematically represented as

         v = \frac{d}{t}

Substituting this into the formula acceleration

        a = \frac{d}{t^2}

making t the subject

         t = \sqrt{\frac{d}{a} }

substituting value

      t = \sqrt{\frac{8}{8.78}}

     t = 0.9545 \ s

Now the linear velocity is

       v = \frac{8}{0.9545}

       v = 8.38 m/s

The angular velocity is  

       w = \frac{v}{r}

So

       w = \frac{8.38}{1.5}

        w = 5.59 rad/s

Generally 1 radian is equal to  0.159155 rounds or turns

        So  5.59 radian is  equal to x

Now x is mathematically obtained as

         x = \frac{5.59 * 0.159155}{1}

            = 0.8892 \ rounds

 Also

      60  second =  1 minute

So   1 second  = z      

Now z is mathematically obtained as

         z = \frac{ 1}{60}

            z = 0.01667 \ minute

Therefore

              w = \frac{0.8892}{0.01667}

              w = 53.35 \ rounds /minute

           

8 0
3 years ago
What would the person’s mass be on the earth? Part B pls
Dafna1 [17]

Answer:

I hopes it helps

thank you

4 0
3 years ago
Parents have a major role in observing how young children grow at home. Create and discuss simple developmental monitoring tips
Rudik [331]

Answer:

by observation of their children

4 0
2 years ago
How to find acceleration in non uniform motion. Please give two ways
Olenka [21]

<u>The two ways to  find acceleration in non uniform motion are as follows:</u>

  • By Graphs
  • By Calculus

<u>Explanation:</u>

Non-uniform acceleration comprises the most common description of motion. Acceleration refers to the rate of changes of velocity per unit time. Basically, it implies that acceleration changes during motion. This variety can be communicated either as far as position (x) or time (t).

Accordingly, non-uniform acceleration motion can be carried out in 2 ways:

  • By Calculus
  • By graphs

Calculus analysis is general and accurate, but limited to the availability of speed and acceleration expressions. It is not always possible to get the expression of motion attributes in the form "x" or "t". On the other hand, the graphic method is not accurate enough, but it can be used accurately if the graphic has the correct shapes.

The use of calculations involves differentiation and integration. Integration enables evaluation of the expression of acceleration of speed and expression of movement at a distance. Similarly, differentiation allows us to evaluate expression of speed position and expression speed to acceleration.

6 0
3 years ago
A heat engine operates between two reservoirs at 300K. During each cycle, it absorbs 200 calories from the high temperature rese
yanalaym [24]

(a) Zero

The maximum efficiency (Carnot efficiency) of a heat engine is given by

\eta=1-\frac{T_C}{T_H}

where

T_C is the low-temperature reservoir

T_H is the high-temperature reservoir

For the heat engine in the problem, we have:

T_C = 300K

T_H = 300K

Therefore, the maximum efficiency is

\eta=1-\frac{300}{300}=0

(b) Zero

The efficiency of a heat engine can also be rewritten as

\eta = \frac{W}{Q_H}

where

W is the work performed by the engine

Q_H is the heat absorbed from the high-temperature reservoir

In this problem, we know

\eta=0

Therefore, since the term Q_H cannot be equal to infinity, the numerator of the fraction must be zero as well, which means

W = 0

So the engine cannot perform any work.

5 0
3 years ago
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