Physics kinematics

Two trains leave different cities heading toward each other at different speeds. A train A, traveling
144 km/h, leaves city A heading toward city B, 8200 m away. 50 seconds later, a train B, traveling
216 km/h, leaves city B heading toward city A. a) In how many seconds will train A meet train B?
b) How far from city A do they meet?

ans:a) 112 s, b) 4480 m

hey, first you have to find the distance travelled by A in 50 seconds.
d=speed * time
speed in m/s=144 * 1000/60 * 60= 40
d=40 * 50 = 2000m
so distance travelled by A in 50s= 8200-2000= 6200m

convert speed in km/h of train B to m/s
=216 * 1000/ 60 * 60 =60m/s
t=6200/60+40=6200/100=62 seconds
The time taken by Train A to meet B= 62+50=112s

b.) distance=speed of A * time
=40 * 112=4480m