The big mall near Sally and Amy's city has extended their operating hours to accommodate the huge crowds expected for the After Thanksgiving Sale. In their eagerness to beat the crowd, Sally forgets to turn off the headlights when she gets out of the car at the mall parking lot. The headlights in her car require 37.0 W of power each, and her 12.0 V car battery is rated at 92.0 A · h. When the two friends come back to the car after a long and successful shopping spree, they find that the car refuses to start as the battery is now completely discharged. How long were they in the mall? Assume that they come out just as the battery dies. h

The big mall near Sally and Amy's city has extended their operating hours to accommodate the huge crowds expected for the After Thanksgiving Sale. In their eagerness to beat the crowd, Sally forgets to turn off the headlights when she gets out of the car at the mall parking lot. The headlights in her car require 37.0 W of power each, and her 12.0 V car battery is rated at 92.0 A · h. When the two friends come back to the car after a long and successful shopping spree, they find that the car refuses to start as the battery is now completely discharged. How long were they in the mall? Assume that they come out just as the battery dies. h

University Physics Volume 2

18th Edition

ISBN:9781938168161

Author:OpenStax

Publisher:OpenStax

Chapter10: Direct-current Circuits

Section: Chapter Questions

Problem 12CQ: Semi-truck or trucks use four large 12-V batteries. The starter systemrequires 24 V, while normal...

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Integrated Concepts (a) Assuming 95.0% efficiency for the conversion of electrical power by the motor, what current must the 12.0-V batteries of a 750-kg electric car be able to supply: (a) To accelerate from rest to 25.0 m/s in 1.00 min? (b) To climb a 2.00 102-m- high hill in 2.00 min at a constant 25.0-m/s speed while exerting 5.00 102 N of force to overcome air resistance and friction? (c) To travel at a constant 25.0-m/s speed, exerting a 5.00 102 N force to overcome air resistance and friction? See Figure 20.44.
Semi-truck or trucks use four large 12-V batteries. The starter systemrequires 24 V, while normal operation of the truck’s other electrical components utilizes 12 V. How could the four batteries be connected to produce 24 V? To produce 12 V? Why is 24 V better than 12 V for starting the truck’s engine (a very heavy load)?
(a) What is the average power output of a heart defibrillator that dissipates 400 J of energy in 10.0 ms? (b) Considering the high-power output, why doesn’t the defibrillator produce serious bums?
The- pair of capacitors in Figure P28.63 are fully charged by a 12.0-V battery. The battery is disconnected, and the switch is then closed. Alter 1.00 ms has elapsed, (a) how much charge remains 011 the 3.00-F capacitor? (b) How much charge remains on the 2.00-F capacitor? (c) What is the current in the resistor at this time?
Assume that global lightning on the Earth constitutes a constant current of 1.00 kA between the ground and an atmospheric layer at potential 300 kV. (a) Find the power of terrestrial lightning. (b) For comparison, find the power of sunlight falling on the Earth. Sunlight has an intensity of 1 370 W/m2 above the atmosphere. Sunlight falls perpendicularly on the circular projected area that the Earth presents to the Sun.
Figure P18.37 shows a simplified model of a cardiac defibrillator, a device used to patients in ventricular fibrillation. When the switch S is toggled to the left, the capacitor C charges through the resistor R .When the switch is toggled to the right, the capacitor discharges current through the patients torso, modeled as the resistor Rtorso, allowing the hearts normal rhythm to be reestablished. (a) If the capacitor is initially uncharged with C = 8.00 F and = 1250 V, find the value of R required to charge the capacitor to a voltage of 775 V in 1.50 s. (b) If the capacitor is then discharged across the patients torso with, Rtorso = 1250 , calculate the voltage across the capacitor after 5.00 ms. Figure P18.37
Figure P18.37 shows a simplified model of a cardiac defibrillator, a device used to patients in ventricular fibrillation. When the switch S is toggled to the left, the capacitor C charges through the resistor R .When the switch is toggled to the right, the capacitor discharges current through the patients torso, modeled as the resistor Rtorso, allowing the hearts normal rhythm to be reestablished. (a) If the capacitor is initially uncharged with C = 8.00 F and = 1250 V, find the value of R required to charge the capacitor to a voltage of 775 V in 1.50 s. (b) If the capacitor is then discharged across the patients torso with, Rtorso = 1250 , calculate the voltage across the capacitor after 5.00 ms. Figure P18.37
An electric eel generates electric currents through its highly specialized Hunters organ, in which thousands of disk-shaped cells called electrocytes are lined up in series, very much in the same way batteries are lined up inside a flashlight. When activated, each electrocyte can maintain a potential difference of about 150 mV at a current of 1.0 A for about 2.0 ms. Suppose a grown electric eel has 4.0 103 electrocytes and can deliver up to 3.00 102 shocks in rapid series over about 1.0 s. (a) What maximum electrical power can an electric eel generate? (b) Approximately how much energy does it release in one shock? (c) How high would a mass of 1.0 kg have to be lifted so that its gravitational potential energy equals the energy released in 3.00 102 such shocks?
Consider a series RC circuit as in Figure P28.38 for which R = 1.00 M, C = 5.00 F, and = 30.0 V. Find (a) the time constant of the circuit and (b) the maximum charge on the capacitor after the switch is thrown closed. (c) Find the current in the resistor 10.0 s after the switch is closed.
In the figure ε1 = 3.24 V, ε2 = 0.829 V, R1 = 4.71 Ω, R2 = 1.75 Ω, R3 = 3.59 Ω, and both batteries are ideal. What is the rate at which energy is dissipated in (a) R1, (b) R2, and (c) R3? What is the power of (d) battery 1 and (e) battery 2?
What is the maximum power that can be consumed by any combination of the 6.0 Ω and 9.0Ω resistors feeding it with a potential of 18 V? a.22 W b.71 W c.90 W d.54 W e.80 W
A capacitor charging circuit consists of a battery, an uncharged 20 μF capacitor, and a 5.6 kΩkΩ resistor. At t = 0 ss the switch is closed; 0.15 s later, the current is 0.46 mA . What is the battery's emf?