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SI Units тексеру.ppt

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The Système International SI Units GEL 2006 More free powerpoints at www. worldofteaching. com The Système International SI Units GEL 2006 More free powerpoints at www. worldofteaching. com

Base Quantity Name Time Length Mass Temperature Electric Current Amount of Substance Luminous Intensity Base Quantity Name Time Length Mass Temperature Electric Current Amount of Substance Luminous Intensity Base Unit Symbol Name t l m T, Ө I n (not in A Level) Symbol second metre kilogram kelvin ampere mole s m kg K A mol candela cd

Physical Quantity velocity acceleration density momentum force pressure work (energy) power electrical charge potential Physical Quantity velocity acceleration density momentum force pressure work (energy) power electrical charge potential difference resistance Defined as : Unit Special Name m/s meter per second

Homogenous Equations • Ep = m g h • J = kg Nkg-1 m Homogenous Equations • Ep = m g h • J = kg Nkg-1 m • Nm = kg kgms-2 kg-1 m • kgms-2 m = kgm 2 s-2 • kgm 2 s-2 = kgm 2 s-2 • This equation is homogenous

Homogenous Equations • v 2 = u 2 +2 ax • m 2 s-2 Homogenous Equations • v 2 = u 2 +2 ax • m 2 s-2 = m 2 s-2 + ms-2 m • m 2 s-2 = m 2 s-2 + m 2 s-2 • This equation is homogenous

Homogenous Equations • F= mv r • N = kg ms-1 m-1 • kgms-2 Homogenous Equations • F= mv r • N = kg ms-1 m-1 • kgms-2 = kgs-1 • This equation is not homogenous

Homogenous Equations • What is missing? ms-1 = kgms-2 = kgs-1 v on rhs Homogenous Equations • What is missing? ms-1 = kgms-2 = kgs-1 v on rhs • The equation should read: • F = mv 2 r

Homogenous Equations • Try these: • Ek = ½ m v 2 J = Homogenous Equations • Try these: • Ek = ½ m v 2 J = kg m 2 s-2 N m = kg m 2 s-2 OK • and v = u + at 2 ms-1 = ms-1 + ms-2 s 2 ms-1 = ms-1 + m Not OK s-1 is missing, so equation should read: V = u + at

Show that these equations are homogenous a) x = ut + ½at 2 b) Show that these equations are homogenous a) x = ut + ½at 2 b) T = 2π√l/g c) v = fλ d) I = n. Ave e) W = ½CV 2 What is missing here? f) F = mv - mu