Question

1. A 150 m long train is moving with a uniform velocity of
45 km/h. The time taken by the trains to cross a bridge of


length 850 m is
(a) 565 s (b) 68 s (c) 80

s (d) 92




ans is c 80 sec


45 kmph
45*1000/3600
12.5


train
150 +850=1000
t=s/v
t=1000/12.5
t=80 s​

Answer 1

Answer:

Total length discovered by train=850m+150m=1000m

Velocity=Dispacement/time

t=s/v

t=1000m / (12.5m/s)

t=80s

Time taken to cross the bridge is 80s

hope this will help you

Answer 2

Provided that:

• Length of train = 150 m
• Velocity = 45 kmph
• Length of bridge = 850 m

To calculate:

• Time taken

Solution:

• Time taken = 80 s

Using concepts

• Total length formula
• Time formula
• Formula to convert kmph-mps

Using formulas:

• Total length = Length 1st + Length 2nd

• Time = Distance/Velocity

• 1 kmph = 5/18 mps

Required solution:

~ Firstly let us calculate the total length that tell us about the whole journey here.

→ Total length = Length 1st + Length 2nd

→ Total length = 150 m + 850 m

→ Total length = 1000 m

• Therefore, distance = 1000 m.

~ Now let us convert kmph-mps as the SI unit of velocity is mps.

→ 1 kmph = 5/18 mps

→ 45 kmph = 45 × 5/18 mps

→ 45 kmph = 225/18 mps

→ 45 kmph = 12.5 mps

• Therefore, velocity = 12.5 mps.

~ Now let us find out the time taken.

→ Time = Distance/Velocity

→ Time = 1000/12.5

→ Time = 10000/125

→ Time = 80 sec

• Therefore, time = 80 sec!

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