Answer: 1.77kg
Explanation:
Using the concept or hooke's law, the force (F) applied to a string is directly proportional its extension (e)
F=ke
K is the elastic constant
If the mass applied initially is 0.59kg i.e 5.9N force, we have
5.9=ke... (1)
If a second block is attached let's say 'm', its force will be 10m, and the extension will become 3e
10m = 3ke ... (2)
Dividing eqn 1 by 2,
5.9/10m = ke/3ke
5.9/10m = 1/3
10m = 5.9×3
m = 5.9×3/10
m = 1.77kg