# What is mechanical motion?

Invite you to learn what mechanical motion is, how to recognize a moving or stationary object, the relativity of motion and rest, in the following article.

## What is mechanical motion?

Mechanical motion is the change in position of an object over time relative to another object called mechanical motion.

Eg:

• Airplane movement in the sky.
• Ship motion at sea.

## How to determine whether an object is in motion or at rest?

### How to know if an object is moving?

An object is said to be in motion when the position of the object relative to the datum changes with time, then the object moves relative to the datum.

There are different ways to tell if an object is moving or not. In Physics, to recognize a moving object, one is based on the position of that object relative to another object chosen as a landmark, called a landmark. If the position of an object changes relative to the datum with time, the object moves relative to the datum.

Eg:

To know if a car is moving on the road, we can compare the position of the car relative to the power pole on the side of the road or compared to the trees on the side of the road. If over time, the position of the car changes relative to the pole, then the car moves.

### How do you know an object is at rest?

An object is said to be at rest when the position of the object relative to the landmark does not change with time, then the object is at rest relative to the landmark.

To identify a moving object, one relies on the position of that object relative to another object chosen as a landmark, called a landmark. If the position of the object does not change relative to the landmark, the object is at rest relative to the landmark.

Any object can be selected as a landmark. Often people choose the Earth and objects associated with the Earth such as houses, trees, kilometer poles… as landmarks.

Eg:

To find out if a person on the side of the road is moving, we can compare that person’s position relative to a roadside pole or to a tree on the side of the road. If over time, the person’s position does not change compared to the electric pole he is standing still.

## Why are motion and rest relative?

Motion and rest are relative depending on the object chosen as a reference.

An object can be in motion relative to one object but at rest relative to another.

Eg:

A driver sitting in a car is stationary relative to the car (relative to the car seat or relative to the passenger) because their position does not change over time relative to the car.

But drivers are in motion relative to the roadside trees because their position changes relative to the roadside trees over time.

Example: Compared to the station, the passengers on the train are in motion (moving with the train) because the passenger’s position relative to the station changes over time.

But compared to the carriage, the passengers on the train are stationary because the position of the passengers does not change over time relative to the carriage.

## Common types of movement

The path drawn by a moving object is called the trajectory of motion.

Depending on the orbital shape, we have two common types of motion:

+ Straight motion: is a motion whose trajectory is a straight line.

+ Curved motion: is a motion whose trajectory is a curve.

Hopefully, the above article has helped you better understand mechanical motion, determining whether an object is moving or stationary.

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