Fundamental Quantities

Something can be measure and expressed by a value is called quantity, and generally it a unit.

A quantity use in science and tecnologi is a call a phisicall quantity.
Examples of physical quantities length, weight and time.

Ekample :

1.What quantity is being measure by this boy ?

2.What quantity is being measure by this man?

3.What quantity is being measure by this woman ?

4.What quantity is being measure by this man ?

The seven of fundamental unit of the International System

Fundamental Quantities	unit	abbreviation	dimension
Length	meter	m	L
Mass	kilogram	kg	M
Time	second	s	T
Temperature	kelvin	K	θ
Amount of substance	mol	mol	N
Luminous intensity	candela	cd	J
Electric current	ampere	A	I

Very large or very small numbers are difficult to express such as the earth’s radius or time between collisions in SI units.

So to make it simple, we use a prefix.

prefix	abbreviatin	factor
exa	E	1018
peta	P	1016
tera	T	1012
giga	G	109
mega	M	106
kilo	k	103
hekto	h	102
deka	da	10

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Particles Motion Kinematics

To reach the orbit, an instrument in the flight control room always monitors the position of the shuttle space an calculates velocity and the acceleration from a given position.

1. Position

Position is the location of a particle relative to a frame of reference and expressed by the vector quantity r.

In a Cartesian coordinate, we use unit vector perpendicular to each other :

Unit vector i ( in x direction)  and unit vector j ( in y direction).

If the particle or object is at point (x,y), then is position expressed as

r = xi + yj

    r = 5 i+ 5 j

Displacement

2. Displacement is the change in position of partikel expressed as a vector quantity Δr
If r0 is the initial position and rt is the final position, then the displacement can be written mathematically as

r0 + Δr = rt 

Δr = rt – r0

Or

Δr = Δxi + Δyj

3. Distance

Distance is the magnitude of displacement traveled by particle a scalar quantity  |Δr| or Δr
Distance can bd write mathematically using Phytagoras theorem.

Δr =      


And the direction of the dicplacement θ is

tg θ =

Example

Δr =      

Δr =      

Δr =      

Δr =      

Δr =  5     

tg θ =  =  = 0, 75

θ = 300

learning physics in physics education site, may be useful

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