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Q: A block of 2 kg slides on a parallel surface at a speed of 4 m/s. It falls on an uncompress spring and presses it until the block becomes completely motionless. The value of kinetic friction is 15N and the spring constant is 10000N/m. spring presses –
  • A. 8.5m
  • B. 8.5cm
  • C. 5.5m
  • D. 5.5cm
Correct Answer: Option D - Let, spring x part is pressed m = 2 kg, k = 10000 N/m and v= 4m/sec. According to question, Mv²/2=kx²/2 0.5×2×42 = 10000×x²×0.5 x²=32/10000, x = 0.056 m x = 5.5 cm (approx)
D. Let, spring x part is pressed m = 2 kg, k = 10000 N/m and v= 4m/sec. According to question, Mv²/2=kx²/2 0.5×2×42 = 10000×x²×0.5 x²=32/10000, x = 0.056 m x = 5.5 cm (approx)

Explanations:

Let, spring x part is pressed m = 2 kg, k = 10000 N/m and v= 4m/sec. According to question, Mv²/2=kx²/2 0.5×2×42 = 10000×x²×0.5 x²=32/10000, x = 0.056 m x = 5.5 cm (approx)