Veto q&a 7 Month22 (1)

Q & A
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Q
A train 100m long is running at the speed of 30 km /hr.
Find the time taken by it to pass a man standing near
the railway time.
⎛ 5 ⎞ 25
Speed of the train = ⎜30 × ⎟m/s
= m/s
⎝ 18 ⎠ 3
Distance moved in passing the standing man = 100 m
100 3
Required time taken = = 100 × = 12Sec
⎛25 ⎞ 25
⎜ ⎟
⎝ 3 ⎠
speed changing in m/s or km/hr
‘x’ km/hr = x × 5 m/s
18
x m/s =
⎛ 18 ⎞
⎜x
× ⎟ km/hr
⎝ 5 ⎠
A Speed of 14 meters per second is the same as
⎛ 18 ⎞
14 m/s = ⎜14
× ⎟km/hr = 50.4 km/hr
⎝ 5 ⎠
In what time will a train 100m long cross an electric
pole, if its speed be 180 km/hr
Length of the train = 100 m
Speed = 180 × 5 = 50 m/s
18 100
Time taken to cross the electric pole = = 2 sec
50
Length of a train ‘L’ meters is passing a pole or
a standing man or a signal light is equal to the
time taken by the train to cover ‘L’ meter.
time taken =
Q A man is standing on a railway bridge which is 180
m long. He finds that a train crosses the bridge in
20 sec by himself in 10 sec. Find the length of the
train and its speed.
Let the length of the train be ‘a’ meter.
Q&A Bonus
length of the train
speed
Then the train cover ‘a’ meter in ‘10sec’ and at
‘180m’ in ‘20 sec’
a a+
180
∴ =
10 20
∴ 20 a = 10(a+180)
10a = 1800
a = 180 m
Length of the train = 180 m
Speed of the train = 180 m/s = 18 m/s
10
18
∴ 18× = 64.8km/hr
time taken by a train of length ‘l’ meters and a
stationary object of length ‘b’ meters is the time
taken by the train cover ‘(l+b)’ meters
Q How long does a train 110 m long running at the
speed of 72 km/hr taken to cross a bridge 132
meters in length
Speed = 72 km/hr = 72× 5 = 20 m/sec
18
Total distance covered = 110+132 = 242 m
⎛242
⎞
∴Required time = ⎜ ⎟ Sec = 12.1 sec
⎝ 20 ⎠
Q The length of the bridge, which a train ‘130 m’
long and travelling at ‘45 km/hr’ can cross in ‘30
seconds’ is
⎛ 5 ⎞ 25
Speed = ⎜45× ⎟=
m/s
⎝ 18 ⎠ 3
time = 30 sec
bridge length be take ‘a’ meter
Then ; a + 130 25
= m/s
30 2
∴2(a+130) = 25 x 30
2a + 260 = 750
a = 245 m
Length of the bridge = 245 m
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