An aeroplane flying horizontally with a speed of 360 kmh−1 releases a bomb at a height of 490 m from the ground. If g = 9.8 ms−2, it will strike the ground at
A
10 km
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B
100 km
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C
1 km
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D
16 km
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Solution
The correct option is B 1 km
First convert speed 360km/hin×m/s
360×10003600=100m/s
When the bomb is dropped, it will have an initial horizontal velocity which is equal to the speed of the plane. So the bomb fall and will travel forward.
Initial horizontal velocity(v)=100m/s
Vertical velocity(u)=0m/s
Height from which bomb is dropped(h)=490m
Time=t secs
Now from 2nd equation of motion h=ut+12gt2
490=0(t)+(12)×9.8×t2
490=4.9×t2
t2=100
t=10secs
So 10secs is the total time which bomb takes to reach the ground by traveling y (let) distance.