For the magnitude of F,
We know,
Young Modulus = Stress / Strain
2 * 10^9 = Force / Area * length /extension
2*10^9 = Force / 3.14* (0.05)^2 * 150 / 5
( In case you are confused about how i got the area, i simply used the formula pi * radius squared. Note that I have converted mm into cm)
2*10^9= Force / 7.85 *10^-3 * 30
30*Force = 2*10^9* 7.85*10^-3
Force = 15.7 *10^ 6/30
Force = 523333.3 N
That's your answer.... Hope u understood it ☺
