Comprehension # 4
When the mass of a sytem is variable, a thrust force has to be applied on it in addition to all other forces acting on it. This thrust force is given by : `vec(F) = vec(v)_(r) (+- (dm)/(dt))`

Here `vec(v)_(r)` is the relative velocity with shich the mass dm either or leaves the system. A car has total mass `50 kg`. Gases are ejected from this backwards with relative velocity `20 m//s`. The rate of ejection of gas is `2 kg//s`. Total mass of gas is `20 kg`. Coefficient of friction between the car and road is `mu = 0.1`.
Car will stop after (from starting) `t =` ........... seconds :-

Options

A. `12.2`
B. `6.4`
C. `10.6`
D. `1.2`

Answer

C