# PHYSICS

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An automobile battery has an emf of 12.6 V and an internal resistance of 0.0500 . The headlights together present equivalent resistance 5.60 (assumed constant).
(a) What is the potential difference across the headlight bulbs when they are the only load on the battery?
V
(b) What is the potential difference across the headlight bulbs when the starter motor is operated, taking an additional 35.0 A from the battery?

• PHYSICS -

a. I=E/(Ri+Rb) = (12.6/(0.05+5.60)=2.23A
V = I*Rb = 2.23 * 5.60 = 12.49 Volts.

b. Vb=E-I*Ri=12.6 - (35+2.23)0.05=10.74
Volts.

• PHYSICS -

(from chapter 12) At a temperature of 0 °C, the mass and volume of a fluid are 825 kg and 1.17 m3. The coefficient of volume expansion is 1.26 × 10 – 3(C ° ) – 1. (a) What is the density of the fluid at this temperature? (b) What is the density of the fluid when the temperature has risen to 20.0 °C?
2.

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