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1. A nurse is using a syringe to inject a medication into a patient's vein.
The syringe has a cross-sectional area of 0.5 cm^2 and the needle has a
cross-sectional area of 0.05 cm^2. If the nurse applies a force of 10 N on
the plunger, what is the pressure exerted by the fluid on the needle tip?
A) 1000 Pa
B) 2000 Pa
C) 10,000 Pa
D) 20,000 Pa
Answer: D) 20,000 Pa
Rationale: The pressure in a fluid is given by P = F/A, where F is the force
and A is the cross-sectional area. The pressure is the same throughout the
fluid, so we can equate the pressure at the plunger and the pressure at the
needle tip. Therefore, F/A = F'/A', where F' is the force at the needle tip
and A' is the cross-sectional area of the needle. Solving for F', we get F' =
F(A'/A) = 10 N (0.05 cm^2 / 0.5 cm^2) = 1 N. Then, using P = F'/A', we
get P = 1 N / 0.05 cm^2 = 20,000 Pa.
2. A nurse is measuring the blood pressure of a patient using a
sphygmomanometer. The cuff is wrapped around the upper arm and
inflated until the blood flow in the brachial artery is stopped. The nurse
then slowly releases the air from the cuff and listens for the sounds of
Korotkoff using a stethoscope. The first sound indicates the systolic
pressure and the last sound indicates the diastolic pressure. If the nurse
hears the first sound when the cuff pressure is 120 mmHg and the last
sound when the cuff pressure is 80 mmHg, what is the patient's blood
pressure?
A) 120/80 mmHg
B) 80/120 mmHg
C) 120 + 80 mmHg
D) 120 - 80 mmHg
Answer: A) 120/80 mmHg
Rationale: Blood pressure is expressed as a ratio of systolic pressure over
diastolic pressure, where systolic pressure is the maximum pressure in the
arteries during a heartbeat and diastolic pressure is the minimum pressure
in the arteries between heartbeats. The cuff pressure represents the
external pressure applied to the artery by the cuff. When the cuff pressure
is equal to or higher than the systolic pressure, no blood can flow through
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