# Mechanical Engineering - Theory of machines - Discussion

3.

In a vibrating system, if the actual damping coefficient is 40 N/m/s and critical damping coefficient is 420 N/m/s, then logarithmic decrement is equal to

 [A]. 0.2 [B]. 0.4 [C]. 0.6 [D]. 0.8

Explanation:

No answer description available for this question.

 Bheemesh said: (Aug 5, 2013) Logarithmic Decrement = 2*(Pi)*Zeta/sqrt(1-zeta^2). Where zeta = Actual damping coefficient/Critical damping coefficient.

 Yas said: (Apr 26, 2014) 2*pi*(40/440)/sqrt(1-(40/440)^2.

 The Sark said: (Oct 5, 2014) 2*pi*(40/420)*(1-(40/420)^2) = 0.59.

 Gaurav said: (Mar 7, 2015) Solution without calculator. Zeta = 40/420 = 0.1 (approx.). Log decrements = 2*pie*0.1/(1-0.1^2) = 2*pie*0.1 = 0.63 (approx..).

 Sarvesh Jaiswal said: (Mar 12, 2015) Ld = 2*3.14*0.1/(1-0.1^2).

 Murtadha Abass said: (Jun 25, 2015) 2*pi*Zeta = 2*3.14*0.09 = 0.565.

 Ankit said: (Sep 6, 2015) 2xpixZeta/sqrt(1-Zeta^2).

 Swagat said: (May 28, 2016) Thanks for all you explanation.

 Pradeep said: (Jul 18, 2016) What is zeta?

 Peviks said: (Jul 20, 2016) Thank you all, it great to understand the solution.

 Rohit said: (Jul 22, 2016) May be Zeta is the damping coefficient.

 Ramu said: (Aug 5, 2016) Zeta is damping factor or damping ratio.

 Vicky Pooraneeswar said: (Nov 7, 2016) Can anyone please explain in a simple way?

 Jithin said: (Dec 8, 2016) @Vicky. Just find logarithmic decrement using following equation. Logarithmic Decrement = 2 * (Pi) * Zeta/sqrt(1-zeta^2). Where zeta is ratio of Actual damping coefficient/Critical damping coefficient.

 Kareena Shah said: (Dec 17, 2016) Perfect answer @Jithin.

 Mohan said: (Feb 8, 2017) Good explanation. Thank you all.

 Nagamalleswarao said: (Feb 16, 2017) Could you please confirm the zeta. Is this zeta is a damping factor or damping coefficient, or both are same?

 Mech Hod said: (Apr 14, 2017) LD = 2 x π x 40 / sqrt(420^2-40^2) = 0.601.

 Pranay Mishra said: (May 11, 2017) I am not getting this, Explain it simple way, please.

 Leela said: (Jun 13, 2017) Cc=2π40/420 = 0.61.

 Prince Kumar said: (Jan 13, 2018) @Pranay Mishra. Logarithmic decrement is the rate through which amplitude of free damped vibration is decreases. It is only for under damped vibration system.

 Mithun Kumar said: (Dec 22, 2018) Since ln(x0/x1)= 2 * π*zeta/√ (1-zeta^2). Where zeta=actual damping coefficient/critical damping coefficient.

 Jeyaseelan said: (Dec 11, 2019) first, find Damping factor = Actual damping coefficient/Critical damping coefficient then Use Damping factor formula to find Lograthemic decrement D.F=(L.D)/(4*pi*pi + L.D*L.D). Where, D.F - Damping factor L.D - Lograthemic decrement pi - 3.16

 Ramesh said: (Jan 25, 2020) THE LOGARITHMIC DECREMENT EQUATION IS; 2π(actual damping co efficient)/root of critical damping co efficient square-actual damping co efficient square. => 2 * 3.14 * 40/ √420^2 *40^2 = 80π/418 = 0.6.

 Hari Prasad said: (Oct 13, 2020) I don't understand can anyone explain in a simple way of method?