Question:medium

If \(6\int_{1}^{x} f(t)dt = 3x f(x) + x^3 - 4, x \geq 1\) then value of (f(2)-f(3)) is :

Show Hint

Equations involving integrals can often be solved by differentiation using Leibniz's rule. Remember to find an initial condition from the original integral equation to determine the constant of integration.
Updated On: Feb 1, 2026
Show Solution

Correct Answer: 3

Solution and Explanation

Concept: Moment of Inertia of a disc is \(I = \frac{1}{2}MR^2\). Mass can be expressed as Density \(\times\) Volume: \(M = \rho (\pi R^2 t)\). Substituting this: \[ I = \frac{1}{2} (\rho \pi R^2 t) R^2 \propto t R^4 \] Step 1: Equate the moments of inertia. \[ t_1 R_1^4 = t_2 R_2^4 \]
Step 2: Solve for ratio of thicknesses. \[ \frac{t_1}{t_2} = \left( \frac{R_2}{R_1} \right)^4 \] Given \(\frac{R_1}{R_2} = \frac{1}{2}\), so \(\frac{R_2}{R_1} = 2\). \[ \frac{t_1}{t_2} = (2)^4 = 16 \] \[ \boxed{\dfrac{t_1}{t_2} = 16} \]
Was this answer helpful?
4