Answer:
to be balanced moments should be equal
4m
Explanation:
![fd = fd \\ 600 \times 2 = 300 \times x \\ \frac{600 \times 2}{300} = x \\ 4m](https://tex.z-dn.net/?f=fd%20%3D%20fd%20%5C%5C%20600%20%5Ctimes%202%20%20%3D%20300%20%5Ctimes%20x%20%5C%5C%20%20%5Cfrac%7B600%20%5Ctimes%202%7D%7B300%7D%20%20%3D%20x%20%5C%5C%204m)
0, Because if they are pulling with equal force then they cancel each other out<span />
It all depends on the wight of the rock to but each 1 sec is 1 mile so about 6 miles
Answer:
C. Copper
Explanation:
F = Force on string
= Intial length of string
A = Area of string
E = Young's modulus of material
Change in length is given by
![\Delta L=\frac{FL_0}{AE}](https://tex.z-dn.net/?f=%5CDelta%20L%3D%5Cfrac%7BFL_0%7D%7BAE%7D)
It can be seen that the change in length is inversely proportional to the Young's modulus of the material.
Here
![E_a=0.7\times 10^{11}\ Pa](https://tex.z-dn.net/?f=E_a%3D0.7%5Ctimes%2010%5E%7B11%7D%5C%20Pa)
![E_b=0.91\times 10^{11}\ Pa](https://tex.z-dn.net/?f=E_b%3D0.91%5Ctimes%2010%5E%7B11%7D%5C%20Pa)
![E_c=1.1\times 10^{11}\ Pa](https://tex.z-dn.net/?f=E_c%3D1.1%5Ctimes%2010%5E%7B11%7D%5C%20Pa)
![\\\Rightarrow E_c>E_b>E_a](https://tex.z-dn.net/?f=%5C%5C%5CRightarrow%20E_c%3EE_b%3EE_a)
So, copper will stretch the least.