Motion of an object is if its velocity is constant.
uniform
Understanding Motion with Constant Velocity
When an object is in motion, we describe its movement in various ways based on how its velocity changes. The question asks about the nature of motion when an object's velocity is constant.
Velocity is a vector quantity, meaning it has both magnitude (speed) and direction. For velocity to be constant, both the speed and the direction of the motion must remain unchanged over time.
What is Uniform Motion?
Uniform motion is defined as the motion of an object in which the object travels in a straight line and its velocity remains constant over time. This means the object covers equal distances in equal intervals of time in a specific direction.
What is Non-Uniform Motion?
Non-uniform motion is the motion in which the object's velocity changes over time. This change in velocity can occur if:
- The speed changes (accelerating or decelerating).
- The direction changes (even if the speed is constant, like in circular motion).
- Both speed and direction change.
Analysing the Options based on Constant Velocity
The question states that the velocity of the object is constant. Let's look at the options:
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only accelerating: Acceleration is the rate of change of velocity. If velocity is constant, there is no change in velocity. Therefore, acceleration is zero. An object with constant velocity is not accelerating.
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only decelerating: Deceleration is negative acceleration, meaning velocity is decreasing (speed is reducing). If velocity is constant, it's neither increasing nor decreasing in magnitude or changing direction. So, it is not decelerating.
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non-uniform: Non-uniform motion means velocity is changing. The question specifies that velocity is constant. Therefore, the motion cannot be non-uniform.
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uniform: Uniform motion is defined as motion with constant velocity. If the velocity of the object is constant, its motion fits the definition of uniform motion.
Based on the definitions and analysis, if the velocity of an object is constant, the motion is uniform motion.
Summary of Motion Types
| Type of Motion | Velocity | Speed | Direction | Acceleration |
|---|---|---|---|---|
| Uniform Motion | Constant ($\vec{v} = \text{constant}$) | Constant | Constant (straight line) | Zero ($\vec{a} = \vec{0}$) |
| Non-Uniform Motion | Changing ($\vec{v} \neq \text{constant}$) | Can be constant or changing | Can be constant or changing | Non-zero ($\vec{a} \neq \vec{0}$) |
Therefore, if the velocity of an object is constant, its motion is uniform.
Revision Table: Key Concepts in Motion
| Term | Definition | Relationship |
|---|---|---|
| Velocity | Rate of change of displacement (vector: speed + direction) | Changes in velocity lead to acceleration |
| Constant Velocity | Velocity that does not change in magnitude (speed) or direction | Defines uniform motion |
| Uniform Motion | Motion with constant velocity | Occurs when acceleration is zero |
| Non-Uniform Motion | Motion with changing velocity | Occurs when acceleration is non-zero |
| Acceleration | Rate of change of velocity | Zero for uniform motion |
Additional Information: Constant Velocity and Inertia
The concept of constant velocity is closely related to Newton's First Law of Motion, also known as the Law of Inertia. This law states that an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an external force. The motion "with the same speed and in the same direction" precisely describes motion with constant velocity, i.e., uniform motion.
In reality, achieving perfect uniform motion is difficult due to forces like friction and air resistance. However, in physics problems, we often consider ideal situations where objects experience uniform motion.
Important Questions from Motion
The motion of a particle of mass m is described by the relation, y = ut - 1⁄2 gt2, where u is the initial velocity of the particle. The force acting on the particle is
The motion of ______ body is an example of uniformly accelerated motion.
- in a particular direction is velocity.
The motion of the body moving along a circular path is an example of ______.
______ time graph shows speed of an object.
