An object travels 10km at a speed of 100 m/s and another 10km at 50 k/s. The average speed over the whole distance is:-

Options

A. mgd
B. `sqrt(2gd)`
C. `2sqrt(g//d)`
D. `2sqrt((mg)/(d))`

Answer

B

Explanation

Initial velocity that is thrown down =v=`v_("initial")`
Distance travelled =d, Acceleration=g
`v^(2)-u^(2)=2as`.
i.e., `v_("final")^(2)=v_("initial")^(2)+2gd`
`therefore_("final")=sqrt(v_("initial")^(2)+2gd)`
Option is not given.
Only if `v_("initial")` has been zero, it would have been
`sqrt(2gd)`