Q. If $x = A\cos{4t} + B\sin{4t}$, then $\frac{d^{2}x}{dt^{2}}$ is equal to

A) $- 16\ x$
B) $16\ x$
C) $x$
D) $- x$
Explanation

(a)
Given, $x = A\cos{4t} + B\sin{4t}$ …(i)
$\Rightarrow$ $\frac{dx}{dt} = - 4A\sin{4t} + 4B\cos{4t}$
$\Rightarrow$ $\frac{d^{2}x}{dt^{2}} - 16A\cos{4t} - 16\ B\sin{4t}$
$\Rightarrow$ $\frac{d^{2}x}{dt^{2}} = - 16x$ [from Eq. (i)]

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.