Question

Which of the following is/are examples of linear motion?
A. Motion of a molecule of a gas.
B. Motion of a stone falling from a certain height.
C. Motion of swing
D. Motion of a clock hand

Answer 1

Hint: First, understand what the linear motion is. The name itself has meaning. Linear means straightest and motion means displacement/momentum. A linear motion if the body moves along the straight line then its motion. Understand the different types of motion. According to the definition of linear motion, categorize which of the given examples is of linear motion. State the type of motion of the given examples.

Complete answer:
Definition of linear motion:
If the body moves along the straight line then its motion is called a linear motion.
The gas molecules in a container filled with gas don’t have any predetermined direction of motion, they move randomly. Thus they perform a random motion.
The stone falling from a certain height falls in the straight line, thus it performs a linear motion.
The swing moves along a curved path as it is tied to a fixed point, therefore it is not a linear motion.
The clock hand rotates around the fixed point, thus it is also not a linear motion. The motion of a clock hand is periodic motion.
Correct option is b, Motion of a stone falling from a certain height.

Additional information:
Types of motion:
1. Circular motion: when the body moves along the circumference of a circle then its motion is called circular motion.
2. Rotational motion: when the body rotates about an axis then it is rotational motion.
3. Periodic motion: if the body repeats its path in an equal interval of time then it is called periodic motion.

Note: Note that linear motion means the body moves along the straight line. Linear motion is also called the rectilinear motion. The motion may be uniform or non-uniform depending on the acceleration of the body. Other examples of linear motion are the motion of the elevator, an athlete running on a straight track etc.