Question

As shown in figure, a spring attached to the ground vertically has a horizontal massless plate with a 2kg mass in it. When the spring (massless) is pressed slightly and released, the 2kg mass, starts executing S.H.M. The force constant of the spring is 200 Nm^–1. For what minimum value of amplitude, will the mass loose contact with the plate?(Take g = 10ms^–2) 

(A) 10.0cm 

(B) 8.0cm 

(C) 4.0cm 

(D) For any value less than 12.0cm.

Answer 1

The correct option (A) 10.0cm  

Explanation:

given: K = 200N/m

g = 10m/s²

m = 2kg

ω = √(k/m) = √{(200)/2} = 10 (1)

for mass to 100se contact with plate,

mω² A = mg

∴ A = (g/ω²) = {10/(100)} = (1/10) ---- from (1)

∴ A = 0.1 m = 10cm