Question

Which of the following quantities are always positive in a simple harmonic motion?
(a) $\overrightarrow{F}.\overrightarrow{a}.$

(b) $\overrightarrow{v}.\overrightarrow{r}.$

(c) $\overrightarrow{a}.\overrightarrow{r}.$

(d) $\overrightarrow{F}.\overrightarrow{r}.$

Answer 1

$\left(a\right)\stackrel{\rightharpoonup }{F}.\stackrel{\rightharpoonup }{a}$

As the direction of force and acceleration are always same, $\stackrel{\rightharpoonup }{F}.\stackrel{\rightharpoonup }{a}$is always positive.