Question

a train runs at 72 km/hr how far distance will it cover in 30 seconds

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Answer 1

Answer:

750/9= 90/t

= 9×90/75

= 54/5

= 10hrs 48 min

Answer 2

Answer:

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600 m

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Explanation:

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Given that the speed of a train is 72km/h.

We need to Find: how much distance will it cover in 30 seconds.

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[ Let's convert 72km/h into m/s, so that we can find the distance covered for 30 seconds easily. ]

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• 1 km = 1000m

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[ Now, as we know 1km is same as 1000m. So, we can multiply 72km/h to 1000m/h to cancel km. Note that we are indirectly multiplying with 1, so it will not change the value of the fraction. ]

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$\implies \dfrac{72~km}{h} \times \dfrac{1000~m}{km}$

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$\implies \dfrac{72}{h}\times 1000~m$

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$\implies \dfrac{72000~m}{h}$

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[ Now, we've got our speed in m/h, we need to convert it in m/s, so, we can repeat the same thing we did with the km. ]

• 1 h = 3600 s

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$\implies \dfrac{72000~m}{h} \times \dfrac{h}{3600~s}$

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$\implies 72000~m \times \dfrac{1}{3600~s}$

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$\implies \dfrac{72000~m}{3600~s}$

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We've got the speed in m/s, now we can simplify it.

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$\implies \dfrac{720\!\!{\not{0}}\!\!{\not{0}}~m}{36\!\!{\not{0}}\!\!{\not{0}}~s}$

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$\implies \dfrac{720~m}{36~s}$

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$\implies \dfrac{20~m}{s}$

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20m/s is the speed of the train.

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[ Now, as we know the train will move 20 metres in a second, so we can simply find the distance covered by the train in 30 seconds. ]

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• Distance travelled in 1 second = 20m
• distance travelled in 30 seconds = 20 × 30 = 600 m

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600 m is the distance covered by the train in 30 seconds.