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Two persons P and Q start from points A and B respectively as shown in figure. P and Q have speed v = 12 m/s in shown directions towards point O, when the distnace between P and Q is 120m,then Q increases its speed to 15 m/s. then find out who will reach the point O first Two persons P and Q start from points A and B respectively as shown in figure. P and Q have speed v = 12 m/s in shown directions towards point O, when the distnace between P and Q is 120m,then Q increases its speed to 15 m/s. then find out who will reach the point O first
HELLO! Given, Distance of point A from O is 240m.Hence, P has to cover a distance of 240m with a speed of 12 m/s. Time taken by P to reach O = Distance/Speed= 240/12 seconds= 20 seconds. If B takes lesser time, then B will reach O first. Consider the Triangle OBX (name the adjacent side of OA = BX).Here, cos 37 = 240/Hypo [Since cos = Base/Hypotenuse]cos 37 = 4/5 So, 4/5 = 240/h=>h = 60 x 5m = 300m So, B has to cover a distance of 300 m to reach point O. Intial distance between P and Q is 180m.Q changes its speed to 15m/s when the distance between them is 120m.So, when Q changes its speed, it has already travelled 60 m, and has to travel a remaining of 300 – 60 = 240m Q covers first 60m at a speed of 12m/s.So time taken = 60/12 = 5 seconds. Q covers the next 240m at a speed of 15m/s.So time taken = 240/15 = 16 seconds. So, total time taken by Q to reach O = 5 + 16 = 21 seconds. Since reaches O in 20 seconds and Q in 21 seconds, P reaches first.I go for Option (a).
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