A small electric immersion heater is used to heat 100 g of water for a cup of instant coffee. The heater is labeled 200 watts. Calculate the time required to bring all this water from 23.0∘C to 100.0∘C, ignoring the heat losses.

It seems hard to justify spending $4.00 for an LED lightbulb when an ordinary incandescent bulb costs $0.50. To see if it makes sense, compare a 60 W incandescent bulb that lasts 1000 hours to a 10 W LED bulb that lasts 20,000 hours. (These are typical values.) Both bulbs produce the same amount of visible light and are interchangeable.

In recent years, practical hybrid cars have hit the road—cars in which the gasoline engine runs a generator that charges batteries that run an electric motor. These cars offer increased efficiency, but significantly greater efficiency could be provided by a purely electric car run by batteries that you charge by plugging into an electric outlet in your house.But there’s a practical problem with such vehicles: the time necessary to recharge the batteries. If you refuel your car with gas at the pump, you add 130 MJ of energy per gallon. If you add 20 gallons, you add a total of 2.6 GJ in about 5 minutes. That’s a lot of energy in a short time; the electric system of your house simply can’t provide power at this rate.There’s another snag as well. Suppose there were electric filling stations that could provide very high currents to recharge your electric car. Conventional batteries can’t recharge very quickly; it would still take longer for a recharge than to refill with gas.One possible…

Question 20 A 8 A.h lithium-ion cell is charged at 2C (units of C-rate are h¹) from 0% state of charge to 67% state of charge. The cell has a constant internal resistance of 0.01 Q and reversible (entropic heating) is assumed to be negligible. How much heat energy is generated. In the lithium-ion cell as a by-product of this charge process? Give your answer as a positive value in joules (), to the nearest integer.

Question 10. A detective has been called to the scene of a crime where a dead body has just been discovered. The detective arrives at 9:00 AM and begins to investigate. Immediately, the temperature of the body is taken and is found to be 90.3°F. The detective checks the programmable thermostat and finds that the room has been kept at a constant 68.0°F for the past 3 days. After the evidence from the crime scene is collected, the temperature of the body is taken once more and found to be 89.0°F. This last temperature reading was taken exactly one hour after the first one. The following day, the detective is asked "At what time did our victim die?" Assuming that the victim's body temperature was normal (98.6°F) prior to death, what should the detective answer?

15:  Suppose a heart defibrillator dissipates 410 J of energy in 12 ms.            What is the average power output of the defibrillator, in W?

What is the heat produced in a conductor in 4.3 minutes if there is a current of 1.8 A and a resistance of 26 Q? Round the final answer to a whole number.