Q. An electric motor of mass $40\ kg$ is mounted on four vertical springs each having constant at $4000\ Nm^{- 1}.$ The period with which the motor vibrates vertically is
A) 0.314 $s$
B) $3.14\ s$
C) $0.628\ s$
D) $0.56\ s$
Explanation
(a) [image:14_image66.png]
The springs are in parallel
Springs constant $= 4 \times 4000\ Nm^{- 1}$
$M = 40\ kg$
$\therefore$ Period of oscillation,$\ T = 2\pi\sqrt{\frac{40}{16000}}$
$\Rightarrow T = \frac{2\pi}{20} = \frac{\pi}{10} \Rightarrow T = 0.314s$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.