Motion in Physics: A Comprehensive Summary

Motion in Physics

Introduction to Motion

Kinematics is the branch of physics that studies movement. Objects can be in two states: at rest or in motion. An object is in motion when it changes its position over time relative to a fixed reference point. A reference system is something assumed to be at rest, against which movements are described. It's crucial to use a reference system when studying the motion of an object.

Understanding Rest

A body is at rest when its position doesn't change over time relative to other objects we consider stationary. To study movement, we need to know:

• Position: The body's location in space relative to a reference system.
• Trajectory: The line describing the body's movement (straight or curved).
• Distance: The length covered by the body moving between two positions.
• Time: The duration taken to travel the distance.

Types of Motion

Movements are classified based on their trajectory:

• Rectilinear Motion: Movement along a straight path.
• Curvilinear Motion: Movement along a curved path.

Speed and Velocity

Speed is the relationship between the distance traveled and the time taken: v = s / t

• s: space or distance
• t: time taken to travel
• v: speed

If the speed is constant, it's uniform motion. If the speed varies, it's accelerated motion.

Uniform Rectilinear Motion (MRU)

Motion is rectilinear when its path is straight and uniform when its velocity is constant. Escalators, for example, exhibit uniform rectilinear motion.

Acceleration

Acceleration is the change in velocity per unit of time. In uniformly accelerated rectilinear motion, both velocity and acceleration are constant.

Graphical Representation of Motion

Representing motion graphically on Cartesian axes (x and y) provides clear visuals for analysis. These graphs typically relate position to time. Other graphs show velocity versus time, allowing us to determine if the speed is constant or changing, and how those changes occur.