A weighing machine consists of a 2 kg pan resting on a spring having linear characteristics. In this condition of resting on the spring, the length of spring is 200 mm. When a 20 kg mass is placed on the pan, the length of the spring becomes 100 mm. The under formed length L in mm and the spring stiffness K in N/m are
- A. L = 220 & K = 1862
- B. L = 200 & K = 1960
- C. L = 210 & K = 1960
- D. L = 200 & K = 2
Answer: C. L = 210 & K = 1960
Explanation: Change in load = 20 kg. Change in length = 200 - 100 = 100 mm = 0.1 m. K = F/x = 20*9.8 / 0.1 = 1960 N/m. Initial deflection x1 due to pan (2kg) = 2*9 Aug 1960 = 0.01 m = 10 mm. Original Length L = 200 + 10 = 210 mm.