Physics is a discipline that seeks to understand and describe how objects move in space and time. Movement is a fundamental part of our reality, and its study allows us to understand and predict a wide variety of phenomena.
In this section, we will explain the different types of movement that kinematics studies, their basic characteristics and we will provide examples to illustrate each of them.
Uniform rectilinear motion (MRU)
Uniform rectilinear motion, or MRU, is characterized by an object moving in a straight line at a constant speed. In this type of motion, the speed does not change in terms of magnitude or direction, which means that the object travels equal distances in equal time intervals.
Examples
A car traveling on a straight road at a constant speed represents a typical example of MRU. When an athlete runs at a constant speed on a straight track, they are also in MRU.
Uniformly accelerated rectilinear motion (MRUA)
Uniformly accelerated rectilinear motion, or MRUA, involves a constant change in the speed of an object. This change can be positive (increase in speed) or negative (decrease in speed) for equal time intervals.
Examples
The throwing of an object upward and its subsequent free fall due to the force of gravity illustrate the MRUA.
When a vehicle gradually stops on a highway or begins to accelerate after stopping at a traffic light, we are also observing an MRUA.
Uniform circular motion (MCU)
Uniform circular motion, or UCM, involves the movement of an object in a circular path around a fixed point called the center of rotation. In this type of motion, the speed of the object constantly changes, but its angular velocity (the speed of rotation) remains constant.
Examples
A child on a carousel spinning around a central pole represents an everyday MCU example.
The rotation of the steam turbine of a nuclear power plant is also an example of MCU except in the start, stop or power variation phases of the reactor.
In astronomy, planets move in circular orbits around the Sun, which is also a type of uniform circular motion.
Uniformly Accelerated Circular Motion (MCUA)
Uniformly accelerated circular motion, or MCUA, involves a constant change in the angular velocity of an object. This means that the object's rotation speed constantly increases or decreases over equal time intervals.
Examples
When a wheel rotates and its angular velocity gradually increases, we are witnessing an MCUA.
Likewise, an object in an orbit, such as an artificial satellite that changes its angular velocity as it moves around the Earth, illustrates this type of motion.
Parabolic movement
Parabolic motion is a combination of horizontal and vertical motion that results in a parabola-shaped path. In this type of movement, an object moves along a curved path.
Examples
The throwing of a baseball that follows a parabolic path before falling is a typical example of parabolic motion.
Similarly, a projectile fired from a cannon follows a parabolic trajectory before hitting a target.
Wave motion
Wave motion involves the propagation of a disturbance through a medium or even in a vacuum in the form of waves. These waves can be of two types:
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Transverse waves, where the vibration is perpendicular to the direction of propagation.
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Longitudinal waves, where the vibration is parallel to the direction of propagation.
Examples
Sound waves traveling through air are examples of wave motion. Also, waves on the surface of a lake or sea represent undulatory waves.
Electromagnetic radiation, which includes visible light, radio waves, X-rays, gamma rays, and other forms of radiation, propagates as electromagnetic waves through space. These electromagnetic waves consist of oscillating electric and magnetic fields that vary in time and space.
