COMEDK2015PhysicsMechanical Properties of Solids
A crane with a steel cable of length 11 ~m and radius 2.0 ~cm is employed to lift a block of concrete of mass 40 tons in a building site. If the Young's modulus of steel is 2.0 10¹¹ ~Pa , what will be roughly the increase in the length of the cable while lifting the block? (Take, g=10 ~ms ⁻² )
Options
- A0.75 ~cm
- B1.25 ~cm
- C1.75 ~cm
- D2.50 ~cm
Correct answer
C. 1.75 ~cm
Step-by-step solution
Given, length, l=11 ~m Radius, r=2 ~cm Radius, =2 10⁻² ~m Mass, m=40 tons =4 10⁴ ~kg Increase in length, l= ? We know that, Young's modulus, aligned Y &= m g l r²( l) l &= m g l r² Y &= 4 10⁴ 10 11 3.14 (2 10⁻² )² 2 10¹¹ &=1.75 10⁻² ~m &=1.75 ~cm aligned