Veto q&a 7 Month22 (1)

Q A train 800 meters long is running at a speed of 78
km/hr. If it crosses a tunnel in one minute. What is
the length of the tunnel (in meters)
Speed
Time = 1 minute = 60 sec
Let the length of the tunnel be ‘a’ meter
800 + a 65
Then, =
60 3
3 (a+800) = 3900
3a = 3900 - 2400
a = 500
Q A train 150 m long is running with a speed of 68
km/h. In what time will it pass a man who is running
at 8 km/h in the same direction in which the train
is going?
38
⎛ 5 ⎞ 65
= ⎜78 × ⎟ m/sec = m/s
⎝ 18 ⎠ 3
Speed of the train relative to the man = (68-8) km/hr
⎛ 5 ⎞ 50
= ⎜60 × ⎟=
m/s
⎝ 18 ⎠ 3
Time taken by the train to cross the man
50
= Time taken by it to cover 150 m at m/sec
3
3
= 150 × = 9 sec
50
Q A train 220 m long is running with a speed of 59
km/h. In what time will it pass a man who is running
at 7 km/h in the direction opposite to that in which
the train is going?
Speed of the train related to man
= (59+7) km/h = 66 km/h
5 55
= 66 × = m/sec
18 3
Time taken by the train to cross the man
55
= Time taken by it to cover 220 m at m/sec
3
3
= 220 × = 12sec 55
• suppose two trains or two bodies are moving in
the same direction at ‘a m/s’ and ‘b m/s’, where
u>v, then their relative speed = (u-v) m/s
• suppose two trains or two bodies are moving in
the opposite direction at ‘a m/s’ and ‘b m/s’ then
their relative speed = (u+v) m/s
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Q A train passes a station platform in 36 seconds and
a man standing on the platforms in 20 seconds. If
the speed of the train is 54 km/hr, what is the length
of the platform
Speed = 54 km/h
5
= 54 × = 15m/sec
18
Length of the train = (15 x 20) m = 300 m
Let the length of the platform be ‘x’ meter
x + 300
Then, = 15
36
⇒ x+300 = 540
∴ x = 240 m
Q A man running at ‘9 km/h’ along side a railway track
is 240 meters ahead of the engine of a 120 meter
long train running at 45 km/h in the same direction.
In how much time will the train pass the man
Speed of train relative to man = 45 - 9 = 36 km/h
5
⇒ 36 × = 10m/sec
18
Distance to be covered = (240 + 120) = 360 m
360
∴Time taken = = 36 sec
10
Q A train 110 meters long is running with a speed of
60 km/h. In what time will it pass a man who is
running at 6 km p/h in the direction opposite to that
in which the train is going
Speed of train relative to man = 60 + 6 = 66 km/h
5 55
66 x = m / s
18 3
∴Time taken to pass the man
⎛ 3 ⎞
= ⎜110 × ⎟sec
= 6sec
⎝ 55 ⎠
Q Two train are moving in opposite direction at 60 km/h
and 90 km/hr. Their length are 1.10 km and 0.9 km
respectively. The time taken by the slower train to
cross the faster train in seconds
Relative speed = 60 + 90
= 150 km/h
5 125
= 150 × = m/sec
18 3
Distance covered = (1.10 + 0.9) km
= 2 km = 2000 m
Required time = Distance
Speed
March 2018