Page 127 - ICSE Math 6

600 × 5
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\ Speed in m s = 18 m s –1
2
= 166 m s –1
3
(b) Speed = 600 km h –1
600 km 600 km
= 1 h = 60 min

= 10 km min –1
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Example 9: A 200 m long train is travelling at a speed of 90 km h . Find the time it will take to
pass:
(a) a pole (b) a 325 m long platform

90 × 5
–1
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Solution: (a) Speed of train = 90 km h = 18 m s = 25 m s –1
To pass the pole, distance to be covered is the length of the train.
Distance 200 m
\ Required time = Speed = 25 m s –1 = 8 s

(b) To pass the platform, distance to be covered is the sum of the length of the train

and the length of the platform.
Distance 200 m + 325 m
\ Required time = Speed = 25 m s –1

525 m
= 25 m s –1 = 21 s

EXERCISE

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1. A car covers a distance of 22 km in 20 minutes. What is its speed in km h ?
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2. The speed of a motorbike is 57 km h . Find the distance covered by it in 2 hours.
3
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3. The speed of a train is 110 km h . How long will it take to cover 3,410 km?
4. An athlete covers 400 m in 40 seconds. Find:
(a) his speed

(b) distance covered by him in 20 minutes
(c) time taken by him to cover 875 m
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5. Find the average speed of a car which travels the first 30 km at a speed of 40 km h and the
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remaining 20 km at a speed of 60 km h .
6. Two friends start running in opposite directions from the same place at the same time at the speed
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of 4 km h and 4 m s respectively. Find the distance between them after 30 minutes.
7. Convert the following speeds.
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(a) 450 km h into m s (b) 144 km h into cm s –1
(c) 35 m s into km h (d) 750 cm s into km h –1
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(e) 1,224 km h into km min (f) 17 km min into m min –1
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