Question

Which of the following statements is/are correct about an object that has zero net external force?
I. The object has no velocity
II. The object has no acceleration
III. The object does not move

• A. I only
• B. II only
• C. I and III only
• D. II and III only
• E. I, II, and III

Answer 1

Answer: (B)

II only

External force acting on a body is $\overrightarrow{F}=m\frac{d\overrightarrow{v}}{dt}$

Thus when $\overrightarrow{F}=0$,

$m\frac{d\overrightarrow{v}}{dt}=0$

$⟹\overrightarrow{a}=0$

$⟹\overrightarrow{v}=constant$

Hence the speed can be non-zero and object will move depending upon the initial velocity. However the acceleration would be zero for sure.