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nevsk [136]
3 years ago
14

Two long copper rods of diameter D 10 mm are soldered together end to end, with solder having a melting point of 650 C. The rods

are in air at 25 C with a convection coefficient of 10 W/m2 K. What is the minimum power input needed to effect the soldering?
Engineering
2 answers:
nadezda [96]3 years ago
5 0

Answer:

Qf 194.2 W

Explanation:

Given data:

Diameter of copper rod D is 0.01 ,

Temperature at junction is Tb = 650 + 273 = 923 K

Temperature of air is 15+273 = 288 K

Tmean = \frac{923 + 288}{2} = 605.5 K

For temperature 605.5 degree celcius thermal conductivity is K = 379 W/m K

Heat transfer is calculated as

qf = \sqrt{hPkAc(Tb -T\infty)}

qf = \sqrt{h\pi D k\frac{\pi}{4} D^2 (Tb -T\infty)}

qf = \sqrt{25 \pi \times 0.01\times 379 \times \frac{\pi}{4} \times 0.01^2(920 -288)}

qf = 97.1 W

Hence, the rate of heat is

Qf = 2qf = 2\times 97.1 = 194.2 W

saw5 [17]3 years ago
3 0

Answer:

125pi  W/m

Explanation:

This is the formula for heat transfer by convection

Q=hA(T2-T1)

Q=Power

h=convection coefficient

A=area

T2= temperature of melting point

T1=temperature of air

Area of tow rods

A=2*pi*D=2*pi*0.01=pi/50

Q=10*(´pi/50)(650-25)

Q=125pi  W/m

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7 0
3 years ago
Read 2 more answers
5. Create a function named second_a that uses a list comprehension. The function will take a single integer parameter n. Find ev
Mekhanik [1.2K]

Answer:

//Program was implemented using C++ Programming Language

// Comments are used for explanatory purpose

#include<iostream>

using namespace std;

unsigned int second_a(unsigned int n)

{

int r,sum=0,temp;

int first;

for(int i= 1; I<=n; i++)

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first = n;

//Check if first digit is 3

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while(first >= 10)

{

first = first / 10;

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Explanation:

The above code segments is a functional program that checks if a number that starts with digit 3 is Palindromic or not.

The program was coded using C++ programming language.

The main method of the program is omitted.

Comments were used for explanatory purpose.

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ahrayia [7]
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Brilliant_brown [7]

Answer:

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