Which one of the following equations of motion represents simple harmonic motion? (Where $k, k_0, k_1$ and $a$ are all positive constants)

Out of the following functions representing the motion of a particle,which represent $SHM$?
$(A)\; y = \sin \omega t - \cos \omega t$
$(B)\; y = \sin^3 \omega t$
$(C)\; y = 5 \cos \left( \frac{3\pi}{4} - 3\omega t \right)$
$(D)\; y = 1 + \omega t + \omega^2 t^2$

The displacement of a particle varies with time according to the relation $x = a \sin \omega t + b \cos \omega t$.

What is the projection of uniform circular motion?

The displacement of a particle is represented by the equation $y = \sin^3 \omega t$. The motion is

$A$ body is moving in a room with a velocity of $20 \ m/s$ perpendicular to the two walls separated by $5 \ m$. There is no friction and the collisions with the walls are elastic. The motion of the body is