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Nostrana [21]
3 years ago
5

Cast-iron cannonballs used in the War of 1812 were occasionally heated for some extended time, so that when fired at houses and

ships, they would set them on fire. If one of these cannonballs with a 20 cm diameter were at a uniform temperature of 1100 K, what heat flux value would exist if it were placed in still air at 300 K? You may assume no thermal radiation effects
Physics
1 answer:
MaRussiya [10]3 years ago
8 0

Answer:

502000W/m²

Heat flux = 800×50.2/20 =

502000W/m²

Explanation:

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Dibuja la gráfica de calentamiento de un kilogramo de plomo que se encuentra inicialmente a 70ºC y pasa a una temperatura final
MariettaO [177]

Answer:

Q= m c_e ΔT and   Q = m L

Explanation:

For this graph of temperature vs energy (heating) we must use two relations

* for when there is no change of state

          Q= m c_e ΔT

* for using there is change of state

          Q = m L

the second expression is a consequence of the fact that all the energy supplied is used to change the state of the solid-liquid and liquid-gas system

the energy supplied is the sum of the energy in each interval

divide the system into intervals determined by the state change points

1) from T₀ = 70ºC to T_f = 327.4ºC, sample in solid-liquid state

           c_e = 128 J / kg ºC

           Q₁ = m c_e (T_f -To)

           Q₁=1  128 (327.4 -70)

           Q₁ = 3.29 10⁴ J

           Q = Q₁ = 3.29 10⁴ J

2) when is it changing from solid to liquid

            L = 2.45 10⁴ J / kg

            Q2 = 1 2.45 10⁴

            Q2 = 2.45 10⁴ J

            Q = Q₁ + Q₂

             Q = 5.74 10⁴ J

3) from to = 327.4ºC until T_f = 1725ºC, sample in liquid state

in the tables the specific heat of the solid and liquid state is the same

             Q3 = m c_e (T_f -To)

             Q3 = 1 128 (1725 -327.4)

             Q3 = 1.79 10⁵ J

              Q = Q₁ + Q₂ + Q₃

              Q = (3.29 +2.45 + 17.9) 10⁴ J

              Q = 23.64 10⁴ J

4) for when it is changing from the liquid state to the gaseous state

             L_v = 8.70 10⁵ J / kg

             Q₄ = m L_v

             Q₄ = 1 8.70 10⁵

             Q₄ = 8.70 10⁵ J

             Q = Q₁ + Q₂ + Q₃ + Q₄

              Q = (3.29 +5.74 + 17.9+ 87.0) 10⁴ J

               Q = 110.64 10⁴ J

5) from To = 1725ºC to T_f = 2000ºC, sample in gaseous state

             Q₅ = m c_e ΔT

             Q₅ = 1 128 (2000 -1725)

             Q₅ = 3.52 10⁴ J

             Q = Q₁ + Q₂ + Q₃ + Q₄ + Q₅

              Q = 114.16 104 J

the following table shows the points to be plotted

         Energy (10⁴ J)  Temperature (ºC)

                  0                     70

                 3.29             327.4

                 5.74             327.4

               23.64           1725

               110.64          1725

                114.16         2000

In the attachment we can see a graph of Temperature versus energy supplied

8 0
2 years ago
Which is the transfer of thermal energy in matter with no overall transfer of matter? If you copy the answer from the last quest
kogti [31]

I believe radiation is the correct answer

8 0
3 years ago
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The four wheels of a car are connected to the car's body by spring assemblies that let the wheels move up and down over bumps an
maksim [4K]

Answer:

The approximate  spring constant is  k =  55533.33 \  N/m

Explanation:

From the question we are told that

   The  mass of the person is  m =  68 \ kg

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Generally according to hooks law  

        F  =  k * x

here the force F is the weight of the person which is mathematically represented as

         F =  m * g

=>    m * g  =  k * x

=>     k  =  \frac{m * g }{x }

=>    k  =  \frac{68 *  9.8}{ 0.012}

=>   k =  55533.33 \  N/m

8 0
3 years ago
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Ksju [112]
Whenever we move, we alter the rate at which we move into the future. This statement is true. 
4 0
2 years ago
A 2-kg toy car accelerates from 0 to 5 m/s2. It
yan [13]
10 joules of work is done by the object
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2 years ago
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