It is given that the increase in length of an elastic spring varies directly as the mass hung from it. If 50 kg produces an increase of 2.5 cm, how many kilograms would produce an increase of 7.5 cm?



Answer :

To solve this problem, we need to use the concept of direct variation. Direct variation implies that if one quantity increases, the other also increases at a constant rate. The relationship can be written as:

[tex]\[ \text{increase in length} = k \times \text{mass} \][/tex]

where [tex]\( k \)[/tex] is the constant of proportionality.

Given:
- An increase in length of 2.5 cm corresponds to a mass of 50 kg.

First, we need to determine the constant [tex]\( k \)[/tex]. We set up our equation with the given values:

[tex]\[ 2.5 = k \times 50 \][/tex]

Solving for [tex]\( k \)[/tex]:

[tex]\[ k = \frac{2.5}{50} \][/tex]
[tex]\[ k = 0.05 \][/tex]

Now that we have the constant [tex]\( k \)[/tex], we can use it to find the required mass that would produce an increase of 7.5 cm. Set up the direct variation equation with the new increase:

[tex]\[ 7.5 = 0.05 \times \text{mass} \][/tex]

Solving for mass:

[tex]\[ \text{mass} = \frac{7.5}{0.05} \][/tex]
[tex]\[ \text{mass} = 150 \text{ kgs} \][/tex]

So, a mass of 150 kgs would produce an increase of 7.5 cms in length of the spring.