(2011?Xuchang second model) after learning the knowledge of elasticity, the class inquiry group using a spring dynamometer and a number of hook yards to study the spring force F and spring

Experimental data can be seen, the spring elongation and the relationship between the tension, can be analyzed from two aspects, one is within the elasticity of the spring, the spring elongation and the tension is proportional to the relationship.

When the spring's elastic force F is 10 and the spring's form variable x is 1;?

When the spring's elastic force F is 20 and the spring's variable of form x is 2;?

The spring's force F is 30 and the spring's variable of form x is 3.

The answer is: F=kx; according to the graph, the two are a straight line through the origin