Question

Which of the following isn't a rectilinear movement?

• A. The motion of planes in the sky
• B. Kids sliding down from a slide
• C. Gravitational forces acting on objects resulting in free fall
• D. A car moving in a circular path

Answer 1

The correct option is D

A car moving in a circular path

Step 1: Explanation of the correct option

In the case of option D,

1. Rectilinear motion is a movement that follows a straight line.
2. The direction of a car traveling on circular course changes at all times. As a result, the rectilinear motion is not the culprit.

Step 2: Explanation for the incorrect options

In the case of option A,

1. Three-dimensional motion is the movement of a particle in space. All three rectangular coordinates vary with time in this motion.
2. If ${\mathrm{x}}_1,{\mathrm{y}}_2,{\mathrm{z}}_3$ are the coordinates of the particle at $\mathrm{t}={\mathrm{t}}_1$​, then ${\mathrm{x}}_2,{\mathrm{y}}_2,{\mathrm{z}}_2$becomes the coordinates of the particle at$\mathrm{t}={\mathrm{t}}_2$.

In the case of option B,

1. Rectilinear motion is demonstrated by a youngster sliding down a slide.

In the case of option C,

1. Gravitational force exerts on an object when it is falling freely. Aside from that, it is affected by air resistance, which works against gravity's power.
2. Despite the fact that gravity is the stronger force, the net force is greater. Air resistance less gravity.

Hence, option (D) is the correct option.