In the figure here, a red car and a green car move toward each other in adjacent

Question

In the figure here, a red car and a green car move toward each other in adjacent lanes and parallel to an x axis. At time t = 0, the red car is at xr = 0 and the green car is at xg = 222 m. If the red car has a constant velocity of 20.0 km/h, the cars pass each other at x = 43.5 m. On the other hand, if the red car has a constant velocity of 40.0 km/h, they pass each other at x = 76.6 m. What are (a) the initial velocity (in km/h) and (b) the (constant) acceleration (in m/s2) of the green car? Include the signs.

Explanation / Answer

1st case
time taken to meet (t1)= 43.5*18/100 = 7.83sec
so using second eqn of motion for greean car.
s = u*t + .5*a*t2

178.5= u*t + .5*a*t2

22.8 = u + 3.915 * a        ....(1)

2nd case

time taken to meet (t2)= 76.6*18/200 = 6.894sec
so using second eqn of motion for greean car.
s = u*t + .5*a*t2

145.4= u*t + .5*a*t2

21.1= u + 3.447 * a        ....(2)

solving above equations:

a= 3.63 m/sec2

u = 8.57 m/sec. both along +ve x- direction

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