From a station two trains start at the same time. One train moves in West direction and other in North direction. First train moves 5km/hr faster than the second train. If after two hours distance between two train is 50km/hr find the average speed of each train!
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Answers
Answer:
Let the average speed of the second train be x km/h.
Thus, the speed of the first train will be (x+5) km/h.
Distance travelled by the first train in two hours =2(x+5) km/h
Distance travelled by the second train in two hours =2x km/h
Using Pythagoras theorem, we have
4x ^2 +4(x+5) ^2 =50 ^2
4x ^2+4x ^2 +40x+100=2500
8x ^2+40x−2400=0
x ^2 +5x−300=0
(x−15)(x+20)=0
x=15,−20
Ignore the negative value of the speed. We have,
Speed of the second train be 15 km/h.
Speed of the first train be (15+5)= 20 km/h.
Speed of first train is 20 Km/h and speed of 2nd train is 15 Km/h
➣ Let the 2nd train travel at X km/h
➣Then, the speed of a train is (5 +x) Km/hour.
➣ let the two trains live from station M.
➣ Distance travelled by first train in 2 hours
= MA = 2(x+5) Km.
➣ Distance travelled by second train in 2 hours
= MB = 2x Km
AB²= MB²+MA²
⟹ 50²=(2(x+5)²+(2x)²
⟹ 2500 = (2x+10)² + 4x²
⟹8x² + 40x - 2400 = 0
⟹x² + 5x - 300 = 0
⟹x² + 20x -15x - 300 = 0
⟹x(x + 20) - 15(x + 20) = 0
⟹ (x + 20)(x -15) = 0
Taking x = 15 , the speed of second train is 15 Km/h and speed of first train is 20 Km/h