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Two trains along the same straight rails...

Two trains along the same straight rails moving the constant speed `60km//hr` and `30km//hr` respectively towards each other. If at time `t=0`, the distance between then is `90km`, the time when they collide is

A

1 hr

B

2 hr

C

3 hr

D

4 hr

Text Solution

Verified by Experts

The relative velocity
`v_("rel")` = 60 – (–30) = 90 km/hr
Distance between the train
` S_("rel" = 90 km `
` therefore ` Time when they colide
` = (S_(rel))/(V_("rel")) = (90)/(90)= 1 hr `
Hence correct answer is (a)
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