Question

Identify the incorrect statement:

• A. Distance is always a positive quantity
• B. Displacement may be negative
• C. If displacement is zero, distance travelled by body will always be zero
• D. Distance will be continously increasing for a moving body

Answer 1

The correct option is C If displacement is zero, distance travelled by body will always be zero

Displacement of a body may be $+ve,-ve$ depending upon the choice of origin and direction of motion of body.
If a body moves along $-ve$ $x-$axis then its displacement will be $-ve$.
If a body moves such that initial and final position are same i.e body arrives back at its initial position, then displacement will be zero.
$\Rightarrow \Delta x=x_f-x_i=x_i-x_i=0$

Distance is always a positive quantity, and if a body is moving then no matter wether it is going towards $+ve$ or $-vex-$axis, distance travelled will keep on increasing.
Ex: If a body is moving on a circular path, and arrives back to the initial position after $1$ revolution then,
$\text{Displacement}=0$
But distance travelled is,
$S=2\pi r$
$\therefore$Option $\left(c\right)$ is incorrect.