width and thickness of two iron rails between two stations 5 km. apart are 20 cm. and 15 cm. If dens

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16 Nov 2011 rail

width and thickness of two iron rails between two stations 5 km. apart are 20 cm. and 15 cm. If density of iron is 7200 kg/m^3, then total iron used to make the 2 rails will be

OPtion

1) 1560000 kg
2) 1080000 kg
3) 1240000 kg
4) 1540000 kg
5) 2160000 kg
6) 2540000 kg
7) 2820000 kg
8) 1860000 kg
9) 3040000 kg
10) none of these

Solution

total mass = number of rails * volume * density
= 2 * 5000 * 0.2 * 0.15 * 7200
= 10000 * 0.03 * 7200
= 300 * 7200 = 2160000 kg

Correct Option: 5 Best Solution (3)