Question

When operating, the ride has a maximum angular speed of $\frac{\sqrt{19}}{5}rad/s$. How much is the rod stretched (in $\mu m$) then?

Answer 1

The force on steel rod here is centrifugal force $F=m{\omega }^{2}l$, where $m$ is mass of the airplane shaped car, $\omega =\frac{\sqrt{19}}{5}$ is the angular speed, and $l=20m$ is the length of the rod. Area $A=8\times {10}^{-4}{m}^2$, Young's modulus is $Y=2\times {10}^{11}N/m^2$

As elongation of rod is given as $\Delta l=Fl/YA=m{\omega }^2{l}^2/YA$

Mass $m$ is not given here.

To get the required answer of $\Delta l=380$, mass should be $m=200kg$