two car A and B are moving with velocities of `60 kmh^(-1) and 45 kmh^(-1)` respectively. Calculate the relative velocity of A w.r.t B if (i) both cars are travelling eastwards and (ii)car A is travelling eastwards and car B is travelling westwards.

Options

A. `15 km h^(-1)`
B. `45 km h^(-1)`
C. `60 km h^(-1)`
D. `105 km h^(-1)`

Answer

A

Explanation

Velocity of car A w.r.t ground `therefore v_AG = 60 km h^(-1)`
Velocity of car B w.r.t ground `therefore v_BG = -45 km h^(-1)`
Relative velocity of car A w.r.t car B is
`v_AB = v_AG + v_GB = v_AG - v_BG = 15 km h^(-1)` (since `v_GB = -v_BG)`