Question

An object is moving along the positive x-axis with a uniform velocity of 5 $m{s}^{–1}$. Then

• A. The net force must be along the positive x-axis
• B. The net force must be zero
• C. The net force must be along the negative x-axis
• D. The net force is a non-zero constant

Answer 1

The correct option is B The net force must be zero

The object is moving with uniform velocity, which means that the object’s velocity is not changing,
i.e., $\Delta v=0$.
$\therefore$ Acceleration, $a=\frac{\Delta v}{t}=0$
According to second law of motion:
Net force, $\sum F=ma$
$\Rightarrow \sum F=m\times 0=0$
Thus, the net force must be zero.
Hence, the correct answer is option (2).