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?
Correct answer: A. 8.0N
- A. 8.0N
- B. 28N
- C. 160N
- D. 400N
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.
This question appeared on the ETEA MDCAT 2013 paper, which you can sit online with every answer explained.
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