A defibrillator is used by emergency medical staff to shock the heart of an accident victim by applying a 10,000- $\mathrm{V}$ potential difference across the victim's chest.

(a) If the defibrillator has an internal resistance of $10 \Omega$ and the victim's heart has a resistance of $300 \Omega$, what is the current that passes through the victim's heart the moment the defibrillator is discharged?

(b) If the defibrillator delivers this current over a $10-\mathrm{ms}$ time interval, how many electrons pass through the heart during this process?

While playing on her swing set, 10-year-old Yasmin falls and breaks her right leg. At the emergency room, the physician tells Yasmin's parents that the proximal end of the tibia, where the epiphysis meets the diaphysis, is fractured. The fracture is properly set and eventually heals. During a routine physical when she is 18 , Yasmin learns that her right leg is $2 cm$ shorter than her left, probably because of her accident. What might account for this difference?

A vehicle is stuck on the railroad tracks as a 430,000 lb locomotive is approaching with a speed of 75 mph. As soon as the problem is detected, the locomotive’s emergency brakes are activated, locking the wheels and causing the locomotive to slide. If the coefficient of kinetic friction between the locomotive and the track is 0.45, what is the minimum distance d at which the brakes must be applied to avoid a collision? What would that distance be if instead of a locomotive, there was a $30 \times 106 lb$ train? Treat the locomotive and the train as particles, assume that the railroad tracks are rectilinear and horizontal, and note that only the locomotive’s brakes are applied.

Ambulance response time. Geographical Analysis (Jan. 2010) presented a study of emergency medical service (EMS) ability to meet the demand for an ambulance. In one example, the researchers presented the following scenario. An ambulance station has one vehicle and two demand locations, $\mathrm{A}$ and $\mathrm{B}$. The probability that the ambulance can travel to a location in under 8 minutes is $.58$ for location $\mathrm{A}$ and $.42$ for location $\mathrm{B}$. The probability that the ambulance is busy at any point in time is $.3$. Find the probability that EMS can meet the demand for an ambulance at location B.

B.L., 17, had a compression fracture at the C5-C6 after jumping into a river from a bridge and slamming into a submerged rock. Fortunately, she was saved by a companion who had first-aid expertise and worked to limit any collateral damage. B.L. was unable to move her limbs, feel touch, or have reflexes in her limbs when she arrived at the emergency room. Describe why it is impossible to determine the entire amount of lasting damage during this initial time frame.

(a) Recall Which amendment guaranteed African Americans the right to vote: the Thirteenth, Fourteenth, or Fifteenth?

(b) Apply Information How did each of these three amendments help to expand democracy?

An emergency drain pump, shown in figure, should be able to pump $0.1 \mathrm{~m}^3 / \mathrm{s}$ of liquid water at $15^{\circ} \mathrm{C}, 10 \mathrm{~m}$ vertically up, delivering it with a velocity of $20 \mathrm{~m} / \mathrm{s}$. It is estimated that the pump, pipe, and nozzle have a combined isentropic efficiency expressed for the pump as $60 \%$. How much power is needed to drive the pump?

A patient is admitted to the emergency department with suspected carbon monoxide poisoning. Even though the patient's color is ruddy and not cyanotic, the nurse understands the patient is at a risk for decreased oxygen-carrying capacity of blood because carbon monoxide does which of the following:

1. Stimulates hyperventilation, causing respiratory alkalosis
2. Forms a strong bond with hemoglobin, thus preventing oxygen binding in the lungs
3. Stimulates hypoventilation, causing respiratory acidosis
4. Causes alveoli to overinflate, leading to atelectasis

Determine whether the two random variables, given in the following way, are dependent or independent. Let X denote the number of times a certain numerical control machine will malfunction: 1, 2, or 3 times on any given day. Let Y denote the number of times a technician is called on an emergency call. Their joint probability distribution is given as

$$\begin{matrix} & & & x & \\ \hline & & 1 & 2 & 3 \\ & 1 & 0.05 & 0.05 & 0.10 \\ y & 3 & 0.05 & 0.10 & 0.35 \\ & 5 & 0.00 & 0.20 & 0.10 \end{matrix}$$

You have an emergency, and you ask your employer for a loan. She gives you $\$ 100$. You sign a form indicating that you received the loan and will start repaying it next month. However, you quit the job the following week. Your former manager calls and asks whether you are going to pay back the loan. You indicate that since you are a minor, the contract is voidable, meaning that you do not have to abide by it. Is it a good idea to avoid the contract?

Consider a simple elevator design in which a 15,000 kg car A is connected to a 12,000 kg counterweight B. Suppose that a failure of the drive system occurs (the failure does not affect the rope connecting A and B) when the car is at rest and 50 m above its buffer, causing the elevator car to fall. Model the car and the counterweight as particles and the cord as massless and inextensible, and model the action of the emergency brakes using a Coulomb friction model with kinetic friction coefficient $\mu \mathrm{k}=0.5$ and a normal force equal to 35% of the car’s weight. Determine the speed with which the car impacts the buffer.

You are working in the emergency department (ED) of a community hospital when the ambulance arrives with A.N., an $18$-year-old woman who was caught in a house fire. She was sleeping when the fire started and managed to make her way out of the house through thick smoke. The emergency medical system crew initiated humidified oxygen at $15 \mathrm{~L} / \mathrm{min}$ per nonrebreather mask and started a $16$-gauge IV with lactated Ringer's solution. On arrival to the ED, her vital signs are $100/66, 125, 34$, $\mathrm{SaO}_2 93 \%$. An additional $16$-gauge IV is inserted. She appears anxious and in pain.

$$\begin{aligned} &\text { Laboratory Test Values }\\ &\begin{array}{ll} \text { Hgb } & 20 \mathrm{~g} / \mathrm{dL} \\ \text { Hct } & 51 \% \\ \mathrm{~K} & 4.9 \mathrm{mEq} / \mathrm{dL} \\ \mathrm{Na} & 133 \mathrm{mEq} / \mathrm{dL} \\ \mathrm{Cl} & 100 \mathrm{mEq} / \mathrm{dL} \\ \text { Glu } & 159 \mathrm{mg} / \mathrm{dL} \\ \text { BUN } & 28 \mathrm{mg} / \mathrm{dL} \\ \text { Cre } & 1.0 \mathrm{mg} / \mathrm{dL} \end{array} \end{aligned}$$

Interpret A.N.'s laboratory results.

The length of stay at a specific emergency department in Phoenix, Arizona, in 2009 had a mean of 4.6 hours with a standard deviation of 2.9. Assume that the length of stay is normally distributed. a. What is the probability of a length of stay greater than 10 hours? b. What length of stay is exceeded by 25% of the visits? c. From the normally distributed model, what is the probability of a length of stay less than 0 hours? Comment on the normally distributed assumption in this example.

An emergency cell phone charger requires you to turn a small crank in order to create the energy needed to recharge the phone’s battery. If you turn the crank 120 times per minute, the total number r of revolutions that you turn the crank is given by r = 120t where t is the time (in minutes) spent turning the crank. a. Graph the function and identify its domain and range. b. Identify the domain and range if you stop turning the crank after 4 minutes. Explain how this affects the appearance of the graph.