Which one of the following equations of motion represents simple harmonic motion ? where k, k0, k1 and a are all positive.
- Acceleration = -k(x + a)
- Acceleration = k(x + a)
- Acceleration = - 2x
- Acceleration = -k0x + k1x2
Answer
(3) Acceleration = - 2x
Solution
As per NCERT, a particle executes simple harmonic motion when its acceleration is proportional to its displacement x from the mean position and is always directed towards the mean position:
a = - 2 x
Option (3) has exactly this form.
In (2) the acceleration is directed away from the mean position, and in (4) the x2 term makes the restoring force non-linear, so they are not SHM.
Answer: (3)