Њутн (јединица)

Њутн
Визуелизација једног њутна силе
Информације о јединици
Систем	SI derived unit
Јединица	Force
Симбол	N
Именован по	Sir Isaac Newton
Јединична претварања
1 N у ...	... је једнак са ...
SI base units	1 kg⋅m⋅s−2
Imperial units	0,2248089 lbf

У физици, њутн (енг. newton; симбол: N) је СИ јединица силе, названа по енглеском научнику Исаку Њутну за признање његових дела на пољу класичне механике. Први пут је употребљена око 1904, али је тек 1948. званично прихваћена од Генералне конференције тежина и мера као назив за mks јединицу за силу.

Њутн се дефинише као количина силе потребне за убрзање масе једног килограма кроз један метар у секунди на квадрат.

Њутн је СИ изведена јединица, која се састоји од kg × m ÷ s² у СИ основним јединицама.

Пошто једна дефиниција тежине каже да она представља деловање силе између два предмета услед гравитације, њутн је такође јединица за тежину. Маса једног килограма близу Земљине површине је приближно 9,81 њутна, мада се ова величина разликује за неколико десетина једног процента на Земљиној површини. Сходно томе, предмет масе 9,81^-1 kg (≈101,94 грама) тежи грубо 1 њутн.

Definition

A newton is defined as 1 kg⋅m/s² (it is a derived unit which is defined in terms of the SI base units). One newton is therefore the force needed to accelerate one kilogram of mass at the rate of one metre per second squared in the direction of the applied force. The units "metre per second squared" can be understood as a change in velocity per time, i.e. an increase of velocity by 1 metre per second every second.

In 1946, Conférence Générale des Poids et Mesures (CGPM) Resolution 2 standardized the unit of force in the MKS system of units to be the amount needed to accelerate 1 kilogram of mass at the rate of 1 metre per second squared. In 1948, the 9th CGPM Resolution 7 adopted the name newton for this force. The MKS system then became the blueprint for today's SI system of units. The newton thus became the standard unit of force in the Système international d'unités (SI), or International System of Units.

In more formal terms, Newton's second law of motion states that the force exerted on an object is directly proportional to the acceleration hence acquired by that object, namely:

$F=ma,$

where $m$ represents the mass of the object undergoing an acceleration $a$. As a result, the newton may be defined in terms of kilograms (${\text{kg}}$), metres (${\text{m}}$), and seconds (${\text{s}}$) as

$1\ {\text{N}}=1\ {\frac {{\text{kg}}\cdot {\text{m}}}{{\text{s}}^{2}}}.$

Examples

At average gravity on Earth (conventionally, 7000980665000000000♠g = 9,80665 m/s²), a kilogram mass exerts a force of about 9.8 newtons. An average-sized apple exerts about one newton of force, which we measure as the apple's weight.

1 N = 0.10197 kg × 9.80665 m/s²    (6999101970000000000♠0,10197 kg = 101.97 g).

The weight of an average adult exerts a force of about 608 N.

608 N = 62 kg × 9.80665 m/s² (where 62 kg is the world average adult mass).

Commonly seen as kilonewtons

A carabiner used in rock climbing, with a safety rating of 26 kN when loaded along the spine with the gate closed, 8 kN when loaded perpendicular to the spine, and 10 kN when loaded along the spine with the gate open.

It is common to see forces expressed in kilonewtons (kN), where 1 kN = 1000 N. For example, the tractive effort of a Class Y steam train locomotive and the thrust of an F100 jet engine are both around 130 kN.

One kilonewton, 1 kN, is equivalent to 102,0 kgf, or about 100 kg of load under Earth gravity.

1 kN = 102 kg × 9.81 m/s².

So for example, a platform that shows it is rated at 321 kN (72.000 lb_f), will safely support a 32.100 kg (70.800 lb) load.

Specifications in kilonewtons are common in safety specifications for:

• the holding values of fasteners, Earth anchors, and other items used in the building industry;
• working loads in tension and in shear;
• rock-climbing equipment;
• thrust of rocket engines, Jet engines and launch vehicles;
• clamping forces of the various moulds in injection-moulding machines used to manufacture plastic parts.

Јединице конверзије

Units of force

	newton (SI unit)	dyne	kilogram-force, kilopond	pound-force	poundal
1 N	≡ 1 kg⋅m/s2	= 105 dyn	≈ 0.10197 kp	≈ 0.22481 lbf	≈ 7.2330 pdl
1 dyn	= 10–5 N	≡ 1 g⋅cm/s2	≈ 6994101970000000000♠1,0197×10−6 kp	≈ 6994224809999999999♠2,2481×10−6 lbf	≈ 6995723300000000000♠7,2330×10−5 pdl
1 kp	= 9.80665 N	= 980665 dyn	≡ gn × 1 kg	≈ 2.2046 lbf	≈ 70.932 pdl
1 lbf	≈ 4.448222 N	≈ 444822 dyn	≈ 0.45359 kp	≡ gn × 1 lb	≈ 32.174 pdl
1 pdl	≈ 0.138255 N	≈ 13825 dyn	≈ 0.014098 kp	≈ 0.031081 lbf	≡ 1 lb⋅ft/s2
The value of gn as used in the official definition of the kilogram-force is used here for all gravitational units.

Standard prefixes for the metric units of measure (multiples)

Prefix name	N/A	deca-	hecto-	kilo-	mega-	giga-	tera-	peta-	exa-	zetta-	yotta-
Prefix symbol		da-	h-	k-	M-	G-	T-	P-	E-	Z-	Y-
Factor	100	101	102	103	106	109	1012	1015	1018	1021	1024

Standard prefixes for the metric units of measure (submultiples)

Prefix name	N/A	deci-	centi-	milli-	micro-	nano-	pico-	femto-	atto-	zepto-	yocto-
Prefix symbol		d-	c-	m-	μ-	n-	p-	f-	a-	z-	y-
Factor	100	10–1	10–2	10–3	10–6	10–9	10–12	10–15	10–18	10–21	10–24

Види још

• Дина
• Килограм-сила

Литература

• E Richard Cohen; Tom Cvitas; Jeremy G Frey; Bertil Holstrom; John W Jost, ур. (2007). Quantities, Units and Symbols in Physical Chemistry (PDF). International Union of Pure and Applied Chemistry (3. изд.). Royal Society of Chemistry; 3rd edition. ISBN 0854044337. 

• International Union of Pure and Applied Chemistry (1993). Quantities, Units and Symbols in Physical Chemistry, 2nd edition, Oxford: Blackwell Science. ISBN 0-632-03583-8. Electronic version.
• I. Mills; Tomislav Cvitas; Klaus Homann; Nikola Kallay (јун 1993). Quantities, Units and Symbols in Physical Chemistry. IUPAC (2nd изд.). Blackwell Science Inc. CS1 одржавање: Формат датума (веза)
• Corben, H.C.; Philip Stehle (1994). Classical Mechanics. New York: Dover publications. стр. 28—31. ISBN 978-0-486-68063-7. 
• Cutnell, John D.; Johnson, Kenneth W. (2003). Physics, Sixth Edition. Hoboken, New Jersey: John Wiley & Sons Inc. ISBN 978-0471151838. 
• Feynman, Richard P.; Leighton; Sands, Matthew (2010). The Feynman lectures on physics. Vol. I: Mainly mechanics, radiation and heat (New millennium изд.). New York: BasicBooks. ISBN 978-0465024933. 
• Feynman, Richard P.; Leighton, Robert B.; Sands, Matthew (2010). The Feynman lectures on physics. Vol. II: Mainly electromagnetism and matter (New millennium изд.). New York: BasicBooks. ISBN 978-0465024940. 
• Halliday, David; Resnick, Robert; Krane, Kenneth S. (2001). Physics v. 1. New York: John Wiley & Sons. ISBN 978-0-471-32057-9. 
• Kleppner, Daniel; Kolenkow, Robert J. (2010). An introduction to mechanics (3. print изд.). Cambridge: Cambridge University Press. ISBN 978-0521198219. 
• Parker, Sybil (1993). „force”. Encyclopedia of Physics. Ohio: McGraw-Hill. стр. 107. ISBN 978-0-07-051400-3. 
• Sears F., Zemansky M. & Young H. (1982). University Physics. Reading, Massachusetts: Addison-Wesley. ISBN 978-0-201-07199-3. 
• Serway, Raymond A. (2003). Physics for Scientists and Engineers. Philadelphia: Saunders College Publishing. ISBN 978-0-534-40842-8. 
• Tipler, Paul (2004). Physics for Scientists and Engineers: Mechanics, Oscillations and Waves, Thermodynamics (5th изд.). W.H. Freeman. ISBN 978-0-7167-0809-4. 
• Verma, H.C. (2004). Concepts of Physics Vol 1. (2004 Reprint изд.). Bharti Bhavan. ISBN 978-8177091878. 
• Quinn, Terry (2012). From Artefacts to Atoms: The Bipm and the Search for Ultimate Measurement Standard. Oxford University Press. стр. 133—135. ISBN 978-0-19-530786-3. 
• Kovalevsky, J; Blevin, WR (март 1998). National and international needs relating to metrology : International collaborations and the role of the BIPM. Saint-Cloud, France: Intergovernmental Organization of the Convention of the Metre. ISBN 92-822-2152-0. Приступљено 14. 3. 2013. CS1 одржавање: Формат датума (веза)
• Kovalevsky, J; Kaarls, R (април 2003). Evolving Needs for Metrology in Trade, Industry and Society and the Role of the BIPM (PDF). Saint-Cloud, France: Intergovernmental Organization of the Convention of the Metre. ISBN 92-822-2212-8. Приступљено 14. 3. 2013. CS1 одржавање: Формат датума (веза)
• Taylor, Barry N., ур. (фебруар 1991). „The International System of Units (SI): Approved translation of the sixth edition (1991) of the International Bureau of Weights and Measures publication Le Système International d'Unités (SI)” (PDF). NIST. CS1 одржавање: Формат датума (веза)

Спољашње везе

• Video lecture on Newton's three laws by Walter Lewin from MIT OpenCourseWare