Question

If 13 metres of a uniform iron rod weights 23.4 kg then what will be the weight of 6 metres of the same rod?​

Answer 1

Solution:

Here,

Weight of 13 m of rod=23.4 kg

Weight of 1 m of rod=23.4/13 kg

[less length,less weight]

Weight of 6 m of rod=23.4/13 ×6 kg=10.8 kg

[more length,more weight]

Thus,the weight of 6 m of rod is 10.8 kg.

Alternative method:

Let,the required weight be x kg.

Then,

We know that,

More length of iron rod(
`\red{\uparrow}`) will have the more weight(
`\red{\uparrow}`).

So,using the rule of direct proportion;

i.e. Ratio of length=Ratio of weight

`\displaystyle{ (13)/(6) = \rm(23.4)/(x) }`

`\rm{13x = 6 * 23.4}`

`\rm{x = \displaystyle{ (6 * 23.4)/(13) }}`

`\therefore{x = 10.8}`

Thus,the weight of 6 m long iron rod is 10.8 kg.