Question

the extension in an elastic string varies directly as the weight hung on it. If a weight of 150 g produces an extension of 2.8 cm, what weight would be produce an extension of 19.6 cm?

Answer 1

Definition of Direct proportìon:
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Two quantities x and y are said to vary in direct proportion

if x / y = k or x = ky

where k is a constant .

In this case , If y1 , y2 are the values of y corresponding to

the values x1 , x2 of x respectively , then

x1 / y1 = x 2/ y2

According to the priblem ,

Let

Weight = x , extention = y

x1 = 150 g

y1 = 2.8 cm

x2 = ?

y2 = 19.6 cm

x1 / y1 = x2 / y2

150 / 2.8 = x2 / 19.6

( 150 × 19.6 )/ 2.8 = x2

After cancellation,

1050 = x2

Weight = 1050 g

I hope this helps you.

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