Unlike most of the other muscles in our bodies, the masseter muscle in the jaw, as illustrated in Figure 9.45, is attached relatively far from the joint, enabling large forces to be exerted by the back teeth. (a) Using the information in the figure, calculate the force exerted by the lower teeth on the bullet. (b) Calculate the force on the joint.

Physics Week 8 Chapter 26: Direct Current Circuits Kirchhoff’s Law 1 (Voltage Law) In a closed conducting path, the sum of potential differences is zero ΣV = 0 Ɛ = V 1 V + 2 3 - Ɛ + V 1 V + 2 = 0 3 Kirchhoff’s Law 2 (Current Law) Sum of currents entering is equal to the sum of currents leaving in a circuit junction ΣI = 0 Resistors in Series R eqR + 1 + R 2 3 I is the same through each resistor V is different for each resistor I Req IR + 1R + IR2 3 Ɛ = V 1 V + 2 3 Resistors in Parallel 1/ R eq1/R + 1/R + 1/2 3 I is different through each resistor V is the same for each resistor I = I1+ I 2 I 3 Ɛ / Req Ɛ /R + 1 /R + Ɛ2/R 3 Open Switch – t /RC q = c Ɛ (1-e ) – t /RC I = Ɛ/R e Closed Switch – t /RC V C Ɛ (1-e ) V R Ɛ e – t /RC RC Circuits (Discharging) Switch Open q = q0e – t /RC – t /RC I = 0 e At t = 0, q = 0 At t = infinity, q = c Ɛ At t = RC, q = c Ɛ (0.63) Switch Closed V C V (10e – t /)C – t /RC V R V e 0 At t = 0, VC= 0, V =RƐ At t = infinity, VC= Ɛ, V R 0 At t = RC, V =C0.63 Ɛ, V = R.37Ɛ Power = VI Pbattery ƐI 2 2 PresistorV R = I R = V R / R (dissipated) Pcapacitor V C