# Doubt in mass suspended by spring

1. ### manimaran1605

60
Consider a mass M, suspended by a weightless spring (horizontally or vertically). If I apply a force on the mass M, it executes simple harmonic motion. My question is for small displacement (that is pushed or pulled) according to Hooke's law F=-kx, it is equal to force we applied right?
F=Ma=-kx, Can i apply Newton's 3rd law here? if yes explain? (But According to Newton's third law, action and reaction happens in different bodies right?)

Last edited: Feb 4, 2014