Question

A uniform rod of length 1m and mass 100g is pivoted at one end and hanging vertically.it is displaced through 60° from the vertical.the increase in its potential energy?ans fast...plz​

Answer 1

When,the rod will vertically hanged down at an angle 60°,then the whole rod will move downward.....

When,the rod will vertically hanged down at an angle 60°,then the whole rod will move downward.....In This case will will notice only the centre of mass of the Rod,,which is at it's centre.....

from figure we can clearly say that

decrease in height of centre of mass=L/2 -L/2sin30

=L/2-L/4=L/4

putting L=1

we get

decreas in height=1/4

decrease in potential energy=m×g×decrement in height=.1×10×1/4=1/4=.25

Hence decrease in potential energy is 0.25