Two cars, A and B, travel in the same direction on a straight section of highway. A has a speed of 69.5 km/h, and B a speed of 84.3 km/h (both relative to the earth).



(b) If A is initially 394 m in front of B, how long will it take for B to reach A?

1 answer

Da = 69.5*T
Db = 84.3*T

B will have to travel 394 m(0.394km) farther than A to catch up:

Db = Da + 0.394km
84.3 * T = 69.5 * T + 0.394
84.3T-69.5T = 0.394
14.8T = 0.394
T = 0.02662 h. = 1.60 Min. to catch up.