0

Guest

Courses New

A rod of mass m and length 2R can rotate about an axis passing through O in vertical plane. A disc of mass m and radius R is hinged to the other end P of the rod and can freely rotate about P. When disc is at lowest point both rod and disc has angular velocity w. If rod rotates by maximum angle 60 o with downward vertical, then find w in terms of R and g. (all hinges are smooth) {Ans: (9g/16R) 1/2 }

A rod of mass m and length 2R can rotate about an axis passing through O in vertical plane. A disc of mass m and radius R is hinged to the other end P of the rod and can freely rotate about P. When disc is at lowest point both rod and disc has angular velocity w. If rod rotates by maximum angle 60o with downward vertical, then find w in terms of R and g. (all hinges are smooth) {Ans: (9g/16R)1/2}

Question Image
Grade:12th pass

3 Answers

Ayan
20 Points
6 years ago
In this case the angular momentum of the rod is 1/12*m*(2R)2  = 1/3*m*R2 and the angular momentum of the disc is 1/2*m*R2. Now as the rod and the disc rotates with same angular momentum omega when the disc is at lowest point and the rod rotates maximum with angle 60° then the angular momentum is, omega = √9g/16R
Ayan
20 Points
6 years ago
In this case the angular momentum of the rod is 1/12*m*(2R)2  = 1/3*m*R2 and the angular momentum of the disc is 1/2*m*R2. Now as the rod and the disc rotates with same angular momentum omega when the disc is at lowest point and the rod rotates maximum with angle 60° then the angular momentum is, omega = √9g/16R
Sahil babbar
13 Points
6 years ago
Use mechanical energy conservation note that rotational kinetic energy of the disc remains the same as no torque is there to change it but the translational kinetic energy when rod makes 60degrees is zero for the disc and for the rod the total ke(rotational as it is in pure rotation) is also zero apply it correctly as stated u will get the desired answer if u are not able to pls tell I`ll send the full solution

Think You Can Provide A Better Answer ?

Other Related Questions on Mechanics

View all Questions »

ASK QUESTION

Get your questions answered by the expert for free

Answer and earn gift vouchers

Win Gift vouchers upto Rs 500/-

View courses by askIITians

Design classes One-on-One in your own way with Top IITians/Medical Professionals

Click Here Know More

Complete Self Study Package designed by Industry Leading Experts

Click Here Know More

Live 1-1 coding classes to unleash the Creator in your Child

Click Here Know More

a Complete All-in-One Study package Fully Loaded inside a Tablet!

Click Here Know More