Question

Which motion does not require force to maintain it?

• A. Uniform circular motion
• B. Elliptical motion
• C. Uniform straight line motion
• D. Projectile motion

Answer 1

Answer: (C)

According to Newton's second law of motion
$F=ma$
When body is moving uniformly along a straight line and there is no force of friction, acceleration/retardation of the body $a=0.$
$\therefore F=m$
$a=0$
ie, no external force is required.
For accelerated motion, force is necessary.
In uniform circular motion, elliptical motion and projectile motion direction of velocity changes due to which force is imposed.