The restoring force in ideal SHM is derived from a potential (e.g., -kx), so it is conservative.

The term A is a shift of equilibrium; the oscillatory term B sin(ωt) has amplitude |B|, so the SHM amplitude is B.

Halving the length of a spring halves its length which doubles its spring constant (k ∝ 1/length), so each piece has constant 2K.

LASER produces an intense, coherent and monochromatic beam of light, which distinguishes it from ordinary light sources.

Hooke's law states the restoring force is proportional to displacement and directed towards equilibrium, characteristic of simple harmonic systems.

By definition the restoring force in oscillatory motion acts towards the equilibrium position, opposing displacement.

With T = 0.4 s, ω = 2π/T = 5π rad/s and an initial phase π/2 gives y = A sin(ωt + π/2) = A cos(ωt), so y = 0.5 cos(5π t).

Wave speed in a given medium is determined by the medium's properties and is nearly the same for ultrasonic, infrasonic and audio waves.

By definition of a wavefront, all points on a wavefront are in the same phase of vibration.

Free, damped, and forced are recognized types/descriptions related to resonance phenomena; thus 'All of these' is appropriate.