Answer:
The needed force is 400 N.
Step-by-step explanation:
We need to calculate the force for 1.00 m string
According to graph,
The force applied for stretch from 0.10 to 0.15 is 20 N.
0.10-0.15 = 0.05 m
So, the force applied is 20 N for 0.05 m.
For stretch 0.05 m = 20 N
For stretch 1 m =

Hence, The needed force is 400 N.