physics
posted by Anne .
1)An elastic material has a length of 36cm when a load of 40N is hung on it and a length of 45cm when a load of 60N is hung on it. The original length of spring is?
2)A force of 100N stretches an elastic spring to a total of 20cm. If an additional force of 100N stretches the spring 5cm further,find the natural length of the spring.
3)The total length of a spring when a mass of 20g is hung from its end is 14cm,while its total length is 16cm when a mass of 30g is hung from the same end. Calculate the unstretched length of the spring assuming Hooke's law is obeyed.

225cm