Understanding Motion, Velocity, and Acceleration in Physics
What is Motion?
Motion is a physical phenomenon defined as any change of position in space that bodies in a system experience with respect to themselves or another body, which is taken as a reference. Any body in motion describes a path. The description and study of a body’s motion require determining its position in space versus time. This requires a reference system.
What is a Frame of Reference?
A reference system or framework is a set of conventions used by an observer to measure the position and other physical quantities of an object or physical system in time and space.
What is a Rigid Body?
A rigid body can be defined as one that does not undergo deformations under the effect of external forces, i.e., a system of particles whose relative positions are unchanged. A rigid body is an idealization, which is used to study the effects of kinematics, as this branch of mechanics only studies the objects and not the external forces acting on them.
What is Speed? What are the Units?
Speed is the relationship between distance traveled and time spent traversing it. Its magnitude is designated as v. Speed is a scalar quantity with dimensions of length/time. Speed is measured in the same units as velocity but does not have the nature of this vector. Speed is just the magnitude of the velocity. Common units include:
- Meters per second (symbol: m/s, ms-1) – SI unit
- Centimeters per second (symbol: cm/s, cm s-1)
- Kilometers per hour (symbol: km/h)
- Miles per hour (abbreviation: mph)
- Nautical miles per hour (knot, symbol: kt)
- Mach (1 Mach is the speed of sound, n Mach is n times the speed of sound)
- 1 Mach ~ 340 m/s ~ 1224 km/h
- Speed of light in a vacuum (symbol: c) is a natural unit
- c = 299,792,458 m/s
How Many Systems of Physical Units are There?
There are 8 common systems. The most common are:
International System of Units (SI)
- Meter (m)
- Kilogram (kg)
- Second (s)
- Newton (N)
- Pascal (Pa)
- Joule (J)
- Ampere (A)
- Kelvin (K)
What Does “Word Processing” Mean?
To shift or change somewhat, turning one thing into another, finding an equivalent expression for a proposition, equation, system, etc.
What is Acceleration?
Acceleration is a vector quantity that indicates the rate of change of velocity of a body per unit of time. It is normally represented as a.
How Does Gravity Behave?
Gravity has a theoretically infinite range; however, the force is greater if the objects are near each other, and this force will fade away with distance. The loss of intensity of this force is proportional to the square of the distance that separates them. For example, if an object moves away from another at twice the distance, then the force of gravity will be one-fourth as strong.
Is Vertical Launch Up a Variable Motion?
Yes, because the speed varies.
What Makes an Object Moving with Velocity Stop?
It is varied by changing the direction and speed.
What is Centripetal Acceleration?
Centripetal acceleration is a quantity related to the change in direction of the velocity of a particle in motion when it travels a curved path.
Example of Circular Motion
On a highway, you see a car pass, and you know it moves because the landscape in the background is static. The car moves because the wheels are moving, which is an example of circular motion.
How to Determine if Something is Moving
To know if something moves, you must have a reference point since the movement is related to it. If the distance between the object under observation and the reference point changes, then you can determine that the object moves. If the reference point and the object are moving at the same speed and in the same direction, no movement will be visible. A different reference point will be required to see if the object moves. This is what happens with a geostationary satellite. If you observe it from Earth, the satellite appears static, apparently not moving, but if you watch it from space, it moves with the rotation of the Earth.