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प्रश्न
A bowler throws a cricket ball at a speed of 120 km/h. How long does this ball take to travel a distance of 20 metres to reach the batsman?
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उत्तर
The speed of the cricket ball = 120 km/h
= `(120 xx 1000)/60` m/min ...[∵ 1 km = 1000 m and 1 h = 60 min]
= 2 × 1000
= 2000 m/min
Now, speed in m/s = `2000/60` ...[∵ 1 min = 60 s]
= `200/6`
= `100/3` m/s
So, 20 m can be cover in `20/(100/3)` ...`[∵ "Time" = "Distance"/"Speed"]`
= `60/100`
= 0.6 s
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