. A mass of 2.0 kg is put on a flat pan attached to a vertical spring fixed on the ground as shown in the figure
The mass of the spring and the pan is negligible. When pressed slightly and released the mass executes a simple harmonic motion. The spring constant is 200 N/m. What should be the minimum amplitude of the motion, so that the mass gets detached from the pan?
(Tage g=10 m/s2)
(a) 8.0 cm
(b) 10.0 cm
(c) Any value less than 12.0 cm
(d) 4.0 cm
Best Answer
Ans: b
Solution: Let the minimum amplitude of SHM is a. Restoring force on spring
F = ka
Restoring force is balanced by weight mg of block. For mass to execute simple harmonic motion of amplitude a.
ka = mg
Or a = mg/k
Here, m = 2g, k = 200 N/m, g = 10 m/s2
Hence, minimum amplitude of the motion should be 10 cm, so that the mass gets detached from the pan.
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