Question

An amusement park ride consists of airplane shaped cars attached to steel rods. Each rod has a length of 20.0 m and a cross-sectional area of 8.00 $c{m}^2$. Young's modulus for steel is $2\times {10}^{11}N/m^2.$
b. When operating, the ride has a maximum angular speed of $\sqrt{1}$9/5 rad/s. How much is the rod stretched (in mm) then?

• A. 0.38 mm
  
• B. 0.55 mm
  
• C. 0.45 mm
  
• D. 0.34 mm
  

Answer 1

The correct option is A 0.38 mm

0.38 mm
Sln :
The force that each car exerts on the cable is F = $m{\omega }^2{l}_0=\frac{W}{g}{\omega }^2{l}_0.$
$\Delta l=\frac{F{l}_0}{YA}=\frac{W{\omega }^2{l}_0^2}{gYA}$