Q1. Two trains 140 m and 160 m long run at the speed of 60
km/hr and 40 km/hr respectively in opposite directions on parallel tracks. The
time (in seconds) which they take to cross each other is:
(A)
9 (B) 9.6 (C) 10 (D) 10.8
Ans.- (D) Solution
:- Let S1 = 60 km/hr, S2 = 40 km/hr
D1
= 140 m = 0.14 km, D2 = 160 m = 0.16 km
Time = (D1 + D2)/
(S1 + S2) = (0.14 + 0.16)/ (60 + 40)
Time =
0.3/100 hr = (0.3/100) * 3600
=>
Time = 10.8
Q2. A train speeds past a pole in 15 seconds
and a plateform 100 m long in 25 seconds. Its
Length
is:
(A) 50
m (B) 150 m (C) 200 m (D) Data inadequate
Ans.- (B) Solution :-
Let length of train = x
Speed of train is = x/15
Length = Speed * Time
=> 100 + x = (x/15) * 25
=> x = 150 meters.
Q3. A
train 110 meters long is running with a speed 60 kmph. In what time will it
pass a man?
Who is
running at 6 kmph in the direction opposite to that in which the train is
going?
(A) 5
sec (B) 6 sec (C) 7 sec (D) 10 sec
Ans. - (B) Solution: - Let S1 = 6 kmph, S2
= 60 kmph
Avg. speed = 60 + 6 = 66 kmph = 66*5/18 = 55/3 m/sec
L2 = 110 meters
T = 110 /
(55/3) = 6 sec.
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