# spring is designed to compress 2m when stopping a 1.4✕105 kg train moving at .61 m/s. What's the force constant of the spring?

B: What speed would the train be going if it only compressed the spring 0.640 m?

C: What force does the spring exert when compressed 0.640 m? (the magnitude only.)

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- JimLv 74 years agoFavorite Answer
KE of train being stopped = 1/2mV² = (0.5)(1.4E5)(0.61)² = 0.260E5 J

KE = SPE = 0.260E5 = 1/2kx² = (0.5)k(2)² = 2k

k = 0.130E5 = 1.30E4 N/m ANS A:

SPE = 1/2kx² = (0.5)(0.130E5)(0.640)² = 0.0266E5 = 2.66E3 J

2.66E3 = KE = 1/2mV² = 0.7E5V²

V² = 2.66E3/0.7E5 = 3.80E-2 = 0.0380

V = 0.19 m/s ANS B:

Size of spring force = F = kx = 1.30E4(0.640) = 0.832E4 = 8.32E3 N ANS C:

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