E-STAR - Student

M Motion is the phenomenon in which an object changes its position over time with respect to a fixed reference position, known as frame of reference.
Motion is mathematically described in terms of position, displacement, distance, velocity, acceleration, speed, and time.
The position of an object refers to where it is at any particular time relative to a convenient frame of reference. A frame of reference is an observation point where motions of an object are described.
The reference frame may be at rest or moving at a constant rate with respect to the earth.
Distance is a measure of “the path length of a journey an object has covered during its motion”. Distance is a scaler and its SI unit is m.
Displacement is the measure of “how far an object is out of its initial position.” It is a vector with SI unit m.
If the initial position of an object x0, then the object’s displacement when it is at position x, d = x = ∆x - x₀
The speed of an object tells how slowly or how fast the object is moving. Speed is a scalar, and its SI unit is meter, m.
Average speed, v, is defined as the total distance traveled, S, divide by the total time, t, taken:

The SI unit of speed is meters per second (m/s). Other non-SI units of speed are kilometers per hour (km/h), miles per hour (mph), etc.
Speed at a specific instant in time is called instantaneous speed. A car›s speedometer reads its instantaneous speed.
Velocity can be defined as the rate of change of position with respect to a frame of reference. Thus, average velocity,, is defined as

Velocity is a vector quantity. The SI unit of velocity is meter per second (ms- 1), which is the same as that of speed.
Uniform motion is defined as the motion of an object in which the object travels with a constant speed along a straight line. We say the object is moving with a constant speed if it covers equal distances in equal intervals of time, irrespective of the duration of the time.
The average velocity of an object, undertaking a uniform motion, is the same as its instantaneous velocity at any time.
If an object starts from an initial position x₀ and travels at a constant speed v, then its position at any time t is given by

x = x₀ + vt

d = x - x₀ = vt

The acceleration of an object is defined as the rate of change of its velocity, The average acceleration,

is given as

The SI unit of acceleration is meter per second per second (m/s/s or 1m/s²).
If the velocity of an object, moving along a straight line, changes equally in equal intervals of time, then the acceleration is constant and usually called uniform acceleration.
Equations describing a uniformly accelerated motion when t₀ = 0 and initial velocity v₀, then acceleration (a), velocity (v) and displacement (s) at any time (t) are:

A freely falling object is an object that is falling under the sole influence of gravity.
When an object is undergoing free fall it will accelerate downwards at, g = 9.8m / s² , downwards
Newton’s first law (The law of inerta) states that a body at rest continue to be at rest or a body in uniform motion will continue in uniform motion unless a net external force acts on it. This property of bodies to resist changes in their state of motion is called inertia.
Newton’s second law states that the acceleration of an object is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object. Mathematically, F = ma
Newton’s third law states that for every action force there is an equal and opposite reaction force. According to this law, a single force cannot exist; forces are always in pairs: action-reaction force pairs.
Newton discovered that ALL objects attract each other with a force of gravitational attraction. Gravity is universal. This force of gravitational attraction is directly proportional to the masses of both objects and inversely proportional to the square of the distance that separates their centers.