A spring obeying Book's law has an unstretched length of 50 mm and a spring contant of 400 Nm-01. What is the tension in the spring when its overall length is 70mm?

Explanation

According to Hooke's Law, the force F exerted by a spring is directly proportional to the displacement x from its equilibrium position, which can be expressed as F = kx.In this problem, the unstretched length of the spring is 50 mm. The stretched length is given as 70 mm, so the displacement x is 70 mm - 50 mm = 20 mm, which is 0.02 meters.The spring constant k is given as 400 N/m. Therefore, the tension in the spring is F = 400 N/m * 0.02 m = 8 N.Options B, C, and D are incorrect because they either miscalculate the displacement, misapply the spring constant, or misunderstand the relationship given by Hooke's Law.