Join 60,000+ competitive exam aspirants
or with email
Your Cart
SubtotalтВ╣0
TotalтВ╣0
Examoogle тАв User тАв info@examoogle.com тАв EE-2024-8821
Chapter 1 of 12 тАв Page 1 of 248ЁЯФТ Protected PDF тАв Watermarked
Join 60,000+ competitive exam aspirants
How much time will a train of length 200┬аm, moving at a speed of 72┬аkm/h take to cross another train of length 300┬аm completely, moving at 36┬аkm/h in the same direction?
25 sec
100 sec
50 sec
55 sec
50 sec
Convert speed difference directly to m/s: (72тИТ36)├Ч185тАЛ=10 m/s. Then, time = Total length / Relative speed = (200+300)/10=50 seconds.
Train 1 length L1 = 200 m, Speed v1 = 72 km/h. Train 2 length L2 = 300 m, Speed v2 = 36 km/h. Both moving in the same direction.
t=v1тАЛтИТv2тАЛL1тАЛ+L2тАЛтАЛ
Convert speed difference directly to m/s: (72тИТ36)├Ч185тАЛ=10 m/s. Then, time = Total length / Relative speed = (200+300)/10=50 seconds.
Forgetting that in the same direction, speeds must be subtracted (relative speed), not added; also forgetting to convert km/h to m/s.
Calculate Total Distance
Since both trains cross each other completely, the total distance to be covered is the sum of their lengths.
D=200+300=500┬аm
Calculate Relative Speed
When two objects move in the same direction, the relative speed is the difference between their individual speeds.
vrelтАЛ=72тИТ36=36┬аkm/h
Convert Speed to m/s
Convert the relative speed from km/h to m/s by multiplying by 5/18.
vrelтАЛ=36├Ч185тАЛ=10┬аm/s
Calculate Time
Using the formula for time, substitute the values for distance and relative speed.
t=10500тАЛ=50┬аsec
C is correct because the total distance of 500 meters is covered at a relative speed of 10 m/s, resulting in 50 seconds.
This concept is a precursor to advanced relative motion problems in Physics kinematics, such as two vehicles catching up on a highway.
Get instant step-by-step AI explanations, full shift Previous Year Papers (SSC GD, RRB, SSC JE), and regional rank analysis on the official Examoogle App.
Free Download тАв 100K+ Aspirants