**Answer:**

**maximum length of the specimen before deformation = 200 mm**

**Explanation:**

Hi!

If we have a cylinder with length **L₀ **, and it is elasticaly deformed **ΔL (so the final length is L₀ + ** **ΔL), the strain is defined as:**

And the** tensile stress **is:

Elastic modulus **E** is defined as:

In this case **ΔL = 0.45 mm and we must find maximum L₀. **We know that **A=π*r², r=(3.3/2) mm**. Then:

**Answer:**

Below is the desired C++ program for the problem. Do feel free to edit it according to your preference

**Explanation:**

#include <iostream>

#include <vector>

using namespace std;

void ExactChange(int userTotal, vector<int> &coinVals) {

coinVals.reserve(5);

coinVals[0] = userTotal / 100;

userTotal %= 100;

coinVals[1] = userTotal / 25;

userTotal %= 25;

coinVals[2] = userTotal / 10;

userTotal %= 10;

coinVals[3] = userTotal / 5;

userTotal %= 5;

coinVals[4] = userTotal;

}

int main() {

vector<int> coins;

int value;

cin >> value;

if (value <= 0) {

cout << "no change" << endl;

} else {

ExactChange(value, coins);

if (coins[0] != 0) cout << coins[0] << " " << (coins[0] == 1 ? "dollar" : "dollars") << endl;

if (coins[1] != 0) cout << coins[1] << " " << (coins[1] == 1 ? "quarter" : "quarters") << endl;

if (coins[2] != 0) cout << coins[2] << " " << (coins[2] == 1 ? "dime" : "dimes") << endl;

if (coins[3] != 0) cout << coins[3] << " " << (coins[3] == 1 ? "nickel" : "nickels") << endl;

if (coins[4] != 0) cout << coins[4] << " " << (coins[4] == 1 ? "penny" : "pennies") << endl;

}

return 0;

}

**Answer:**

807.5N

**Explanation:**

The combined mass (m) on the back muscle is 55kg + 30kg = 85kg

Acceleration due to gravity (g) = 9.8m/s²

Therefore the force FB = ma = 85*9.8

FB= 807.5N

**Answer:**

i think it's falsel *not sure*

**Answer:**

a) the actual thermal efficiency is 15.17%

b) the maximum thermal efficiency is 29.55%

**Explanation:**

a) the actual thermal efficiency is for a heat engine is,

E actual = Power obtained / Necessary heat rate as input = P/q

q = F * c * (Tinitial - Tfinal) , F = mass flow rate , c=specific heat of water ( we assume c= 1 cal/gr°C = 4.186 J/gr°C= 4.186 kJ/kg°C)

q = 210 Kg/s * 4.186 kJ/kg°C (150°C - 90 °C) = 52743.6 kW

therefore

E actual = 8000 kW /52743.6 kW = 0.1517 = 15.17%

b) the maximum thermal efficiency for the same heat source and heat sink corresponds to the one of a Carnot engine. Where,

E max = 1 - Tc/Th , Th is the absolute temperature of the hot heat source and Tc is the absolute temperature of the cold heat sink.

therefore

Th= 150°C + 273 °C = 423 K

Tc= 25°C + 273°C = 298 K

thus

E max = 1- 298/423 = 0.2955 = 29.55%