A rock weighing 20N falls from a height of 16m and sinks 0.6m into the ground.From energy considerations,find the average force f between the rock and the ground as the rock sinks.
Suppose the highest point from which the rock falls is A and B is the point into the ground where it sinks.
Now, h=16 m and h'=0.6 m
A non conservative work is done on the rock between A and B.
This work is given by,
W'=-f h'
and dK+dU=W'
0+ [mg (-h') -mgh]=-fh'
or f=mg (h+h') / h'
=20 x (16+0.6) /0.6
=553 N
Now, h=16 m and h'=0.6 m
A non conservative work is done on the rock between A and B.
This work is given by,
W'=-f h'
and dK+dU=W'
0+ [mg (-h') -mgh]=-fh'
or f=mg (h+h') / h'
=20 x (16+0.6) /0.6
=553 N