Question

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Class : X
Ch : 4
Pg : 87,
Example : 15

Why we take Upstream as (18-x)km/h and not (x-18)km/h, and same for downstream??​

Answer 1

dear we take upstream as negative beacuse it is opposite to the gravity of the earth and we take positive to downstream because it's with gravity of the earth

Answer 2

because when you are going downstream , you are going in the direction of the river so the values of your speed will add up and it will be (18+x) and in upstream, you are going in the direction opposite to the river

So the values of speed will subtract as they are contradicting each other.

Hope it helps!^_^

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