A body is thrown vertically upwards. If air resistance is to be taken into account, then the time during which the body rises is.

Options

A. the time ascent `te` the time of desent
B. the time of ascent `lt` the time of descent
C. the time of ascent `gt` the time of descent
D. the time of ascent = the time of descne t

Answer

B

Explanation

Let retardation due to air resistance=a
then for upward journey net retardation=(g+a)
`therefore t_("asc")=sqrt((2h)/(g+a))`
and for down ward journey net acceleration =(g-a)
`therefore t_("desc")=sqrt((2h)/(g-a))`
`therefore t_("asc")ltt_("desc")`