Q. Two particles move along x-axis in the same direction with uniform velocities 8 m/s and 4m/s. Initially the first particle is 21m to the left of the origin and the second one is 7m to the right of the origin. The two particles meet from the origin at a distance of

(a) 35 m

(b) 32 m

(c) 28 m

(d) 56 m

Ans: (a)

Sol: Initial Separation b/w two particles = 21 + 7 = 28 m

Distance travelled by 2nd particle is

S = 4 t …(1)

Hence distance covered by first particle is

S + 28 = 8 t …(ii)

subtracting (i) from (ii)

28 = 4t

t = 7 sec

The distance travelled by 2nd particle (from its initial posituon) = 4 x 7 = 28 m

Distance from Origin = 28 +7 = 35 m