Translations of Encyclopedia about Physics

Physical Units and Quantities

Lift

Lift (previously also referred to as weight) is the coefficient of mass and centrifugal forces which occur as a result of the rotation of the earth.

W = m x g
W = weight
m = mass
g = the gravitational acceleration of the earth

Torque

Torque T is the coefficient of forces and the distance between the location of their effect from the centre of rotation.

T = F x d
T = torque
F = exerted force
D = distance from the centre of rotation

Pressure

Pressure is calculated according to force and the surface area on which the force is applied:

P = F / A
P = pressure
F = applied force
A = the surface on which the force is applied

Force and Motion

The Second Law of Newton

Force F is the coefficient of acceleration and mass
F = m x a

Speed

Speed is the proportion of a trajectory traveled during a time period and that time period.

v = s / t

Constant Acceleration

Acceleration is the proportion of the calculated difference in change of speed and the time interval in which this change took place.

a = (v2 – v1) / t

Impulse

P = m x v
a = acceleration
v = speed
t = time or time period
m = mass
v1 = initial speed
P = impulse
F = applied force
v2 = final speed
s = position after time t (the trajectory along which an object travelled)

Gravity

The force of gravity F is directly proportional to the gravity constant and the mass of two objects and indirectly proportional to the square of their distance d.

F = gravitational force between two objects
G = gravitational constant
m1 = mass of object 1
m2 = mass of object 2
d = distance between the two objects

Friction

The force of friction is directly proportional to the force applied by the object onto itself and the coefficient of friction relating to the coarseness of the surface concerned.

F = x Fn
F = frictional force
= coefficient of friction
Fn = force pressuring the object onto itself

Work

Executed work W is the coefficient between force and the distance along which this force was applied.

W = F x d
W= executed work
F = applied force
d = the distance along which the force is applied

Centripetal Force

Centripetal force is the force which acts on an object in the direction towards the centre of a circle while creating centripetal acceleration and maintaining the object in a circular path. It is directly proportional to the multiple of the second power of the speed and indirectly proportional to the radius of the circle.

F = (m x v x v) / r
F = centripetal force
m = mass of the object
v = speed of travel along the circle’s path
r = radius of the circle

Pressure in Liquids

Pressure in liquids is directly proportional to the consistency of the liquid, the depth of the liquid and the gravitational acceleration of the earth.

P = x g x h
P = pressure
= liquid consistency
h = the height/depth of the liquid level
g = the gravitational acceleration of the earth

Elasticity

Elasticity is the ability of a substance to return to its original shape and size after when tension or pressure deformation forces are no longer applied to it. Stretching is the proportionate applied force provided that the object’s stretch limit is not exceeded.

X F
F = applied force
X = stretching

Laws which Describe the Behaviour of Gases

Boyle’s Law

The volume of gas at a constant temperature is indirectly proportional to pressure.

V 1 / P

Gay-Lassac’s Law

The volume of a set amount of gas under constant pressure is proportional to absolute temperature (in Kelvin).

V T

Law of Ideal Gases

The product of pressure and the volume of gas is directly proportional to temperature. The relative constant is called the gas constant.

P V = R T
V = volume
P = pressure
T = temperature (in Kelvin)
R = gas constant

Electrical Current

Current, voltage, resistance

Resistance R is the quotient of voltage and current. (Ohm’s law)

R = U / I

Output

Output P is the quotient of voltage and current.

P = U x I
I = current
U = voltage
R = resistance
P = output

Optical Image

(the refraction of light when passing through a lens)

The inverse value of the focal distance equals the sum of the inverse value of distance of the image created by the lens and the distance of the object from which the image was made.

f = focal distance of lens/mirror
g = distance of object from which the image was made (the distance between the object and the lens/mirror)
b = the distance of the created image (the distance between the created image and the lens/mirror)

Units and Quantities

SI-units (units of the international unit system - Système International d´Unités)

Physical quantities

Sl unit

Symbol

length

meter

m

weight

kilogram

kg

time

second

s

electrical current

ampere

A

temperature

Kelvin

K

luminous intensity

candle

cd

substance amount

mol

mol

straight angle

radian

rad

spatial angle

steradian

sr

frequency

Hertz

Hz

energy/work/temperature

Joule

J

force

Newton

N

pressure

Pascal (Newton/ m²)

Pa (N. m^–2)

electrical charge

Coulomb

C

voltage

volt

V

electrical resistance

ohm

Units of Measurement

Unit

corresponds to

distance

1 centimetre (cm)

10 millimetre (mm)

1 meter (m)

100 centimetre

1 kilometre (km)

1000 meter

1 nautical mile

1852 meter

Unit measurements

1 kilogram (kg)

1000 grams

1 ton (t)

1000 kilograms

1 metric cent

100 kilograms (q)

1 pound

0,5 kilogram

1 (ct) karat

0,2 g (bei precious stones)

1 karat (ct)

1/24 weight proportion of gold (24ct - pure gold)

Surface measurements

1 square centimetres (cm²)

100 square millimetres (mm² )

1 square metre (m²)

10.000 centimetres square

1 Ar (a)

100 metres square

1 hectare (ha)

10.000 metres square

1 square kilometre (km² )

1.000.000 square metres

Space and volume

1 cubic centimetre (cm³ )

1 millilitre (ml)

1 litre (l)

1000 millilitre

1 cubic metre (m³)

1000 litres

Hollow measurements

1 centilitre (cl)

10 millilitres (ml)

1 decilitre (dl)

10 centilitres

1 litre (l)

10 decilitres

1 decilitre (dal)

10 litres

1 hectolitre (hl)

10 decilitres

1 kilolitre (kl)

10 hectolitres

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