(angular acceleration) Δω dω d2θ β = lim = dt = dt2 Δt (β= ω ω = ω0 + β t 1 θ = ω0 t + β t2 2 ω θ ) ½βt2 ω2 − ω02 = 2 β θ (angular velocity) dθ Δθ ω = lim = dt Δt→0 Δt (ω= ω ( ’ v = v0 + a t ) θ=ωt v θ ’ x = v0 t + x=vt ’ v0 : x t ω0t ω0 : v2 − v02 a= t ) v 1 2 at 2 =2ax ½at2 v0t t t 1 d2θ dt2 = β ( ) t dθ = β t + ω0 dt ( ω0 ) t= ω – ω0 β θ= ω – ω0 2 1 ω – ω0 β( ) + ω0 ( ) β 2 β ω 2 − ω 02 = 2 β θ ω ω = ω0 + β t ( ) t 1 θ = 2 β t2 + ω0 t + θ0 θ0 θ0 = 0 2 x=rθ β: r= ) t dx dθ =r dt dt a=rβ a: ( v=rω r: t β θ x=rθ r dv dω = r dt dt a=rβ □ x a 3 m F a N N: I: β: ( N=Iβ ) ( N=Fr F=ma ) N=mar a=rβ N = m r2 β ( ) I = m r2 r r m □ I β F r N=Iβ I = m r2 a m 4 (ii) ρ m (i) ρ m r r L dL x dx ( ( ) ρdx) di = ρdx x2 L di (I I = ∫ di = ∫0 ρ x2 dx = ρ [ =mr2) x3 L ρL3 ] = 3 3 0 ( di (I =mr2) ρ r2 dL = ρ r2 dL ρdx) di = ρdL r2 I = ∫ di = ) dL = rdθ 2π ( (θ ) 2π dL = ∫0 r dθ = r [θ] 0 = 2 π r m = ρL 1 I = 3 m L2 I = ρ r2 2 π r m=ρ 2πr I = m r2 5 (iii) ρ dr m R r ( dr) di (I =mr2) di = ρ 2πr3 dr R R I = ∫ di = ∫0 ρ 2πr3 dr = 2πρ ∫0 r3 dr = 2πρ R4 4 m = ρ πR2 I= 1 m R2 2 6 ( ( mA ) A B TB A mAa = TA – mAg B mBa = mBg – TB TA = TB = T ( ) + (mA + mB)a = (mB − mA)g mB − mA a= g mA + mB ) A mB B g A B TA r I 0 M a mB mA I= 1 M R2 2 a 7 M(≠0) B A TA < TB TB TA + ** * ** {(mB − mA)g − (mA + mB)a}r2 a= I 1 I= M R2 2 (mB − mA)g a= 1 M + mA + mB 2 β r mAa = TA – mAg mBa = mBg – TB (mA + mB)a = (mB − mA)g + TA – TB TB – TA = (mB − mA)g − (mA + mB)a I β = (TB – TA) r TA A B TB M=0 a a=rβ mB mA a (TB – TA) r2 a= I * 8 a r 2 m f g θ a ma = mgsinθ – f β θ I = ½ m r2 a = r β ma = mgsinθ – f f a = gsinθ – m ma = mgsinθ – ½ ma Iβ=fr ½ ma = f a= 2 gsinθ 3 9
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