Question

A vibrating system consists of mass of 50 kg, a spring with a stiffness of 30 kN/m and . a damper. If damping is 20% of the critical value, the natural frequency of damped vibrations will be 

(a) 16 rad/s 

(b) 20 rad/s 

(c) 24 rad/s 

(d) 28 rad/s

Answer 1

Correct option is (c) 24 rad/s 

m = 50 kg 

s = 30 kN/m = 30000 N/m 

ξ = 0.2

(Critical, ξ_CR = 1, ξ = (0.2)ξ_CR = 0.2)