CameraIcon
CameraIcon
SearchIcon
MyQuestionIcon
MyQuestionIcon
1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

A rod PQ of mass m and length L is hinged at its one end P. The rod is kept horizontal by a massless string tied to end Q. When the string is cut, initial angular acceleration of the rod is


A
3g2L
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
B
gL
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
2gL
No worries! We‘ve got your back. Try BYJU‘S free classes today!
D
2g3L
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

The correct option is A 3g2L
When string is cut, the rod will rotate about hinge point P.
Let the initial angular acceleration be α.


Let Nx & Ny be the hinge forces but they pass through point P, hence their torques about P vanish.

Applying the equation of torque about P,
τ=Iα
τmg=Iα ...(i)
From parallel axis theorem, the MOI of the rod about P,
I=mL212+mL24
Substituting in Eq.(i),
L2×mg=(mL212+mL24)α
mgL2=mL23α
α=3g2L
Initial angular acceleration of the rod about P is 3g2L

flag
Suggest Corrections
thumbs-up
53
Join BYJU'S Learning Program
Join BYJU'S Learning Program
CrossIcon