A particle is in linear simple harmonic motion between two points, A and B, $10 \mathrm{~cm}$ apart. Take the direction from $A$ to $B$ as the positive direction and give the signs of velocity, acceleration and force on the particle when it is
(a) at $3 \mathrm{~cm}$ away from A going towards $\mathrm{B}$, and
(b) at $4 \mathbf{c m}$ away from B going towards $A$.

(a) Positive, Positive, Positive

From the end $A$, the particle is travelling toward point 0. This motion is going from $A$ to $B$, which is the standard positive direction. As a result, the velocity, acceleration, and force measurements are all positive.

(b) Negative, Negative, Negative

From the end $A$, the particle moves toward point 0. The motion is in the traditional positive direction, from $A$ to $B$. As a result, velocity, acceleration, and force all have positive values.