PHY 2 Uworld
The blood leaving the aorta reaches the circle of Willis, a collection of arteries that supplies blood to the brain. Assume that it takes 600 ms for blood to reach the circle of Willis and that its average velocity is reduced to 61 cm/s. What is the average acceleration experienced by the blood?
-67 cm/s^2
A bone sample (specific gravity = 3) completely immersed in isopropyl alcohol (specific gravity = 0.8) is subject to a buoyant force of 4 N. What buoyant force would the same bone sample experience when immersed in water?
5 N Therefore, the ratio of buoyant forces is equal to the ratio of fluid densities: FB,1FB,2=ρ1V1g / ρ2V2g=ρ1/ρ2 Because the bone sample is fully immersed in isopropyl alcohol and water, the above relationship applies: FB,alcohol/FB,water=ρalcohol/ρwater The buoyant force in water FB,water is calculated using the value of FB,alcohol given in the question, 0.8 kg/L for ρalcohol, and the value of ρwater given in the passage: FB,water=ρwater/ρalcohol(FB,alcohol) FB,water=((1 kg/L)/ (0.8 kg/L)) (4 N)=5 N
In a hot air balloon, a flame heats the air inside the balloon and the balloon rises upward. Why does heating the air cause the balloon to rise? A.The heated air becomes less dense, and convection causes it to rise. B.The heated air becomes denser, and convection causes it to rise. C.The radiation created by the flame pushes the air upward. D.The heat transferred by conduction pushes the air upward.
A.The heated air becomes less dense, and convection causes it to rise.
Which of the following statements best explains why the higher dose of gamma-emitting drug has a greater therapeutic response? A.The intensity of the gamma rays is greater. B.The frequency of the gamma rays is greater. C.The velocity of the gamma rays is faster. D.The energy of the gamma rays is greater.
A.The intensity of the gamma rays is greater.
Charge flowing into x ray tube based on graph
According to circuit sign conventions, I is positive in the direction of the flow of positive Q and equals the ratio of Q and Δt: I=Q/Δt The unit for I is the ampere (A), which equals a Q of 1 Coulomb (C) flowing through the circuit in 1 s. Furthermore, this equation can be rearranged to solve for Q: Q= I⋅Δt In this question, I flowing into the x-ray tube equals 100 mA, which is 0.1 A, and Δt for a single x-ray image is 20 ms, which is 0.02 s. Substituting these values into the above equation yields: Q=(0.1 A)(0.02 s)=(0.1 C/s)(0.02 s) Q= 0.002 C= 2mC Therefore, 2 mC flows into the x-ray tube for each x-ray image.
If the density of the drug is known, what additional information is required to calculate the velocity of the drug as it enters the blood vessel? (Note: Assume ideal fluid flow.) A.Pressure in syringe, pressure in blood vessel, and mass of drug B.Pressure in syringe, velocity in syringe, and pressure in blood vessel C.Pressure in syringe, velocity in syringe, and volume of drug D.Velocity in syringe, mass of drug, and volume of drug
B.Pressure in syringe, velocity in syringe, and pressure in blood vessel
What is the temperature change of the renal artery from the RF ablation system described in the passage? (Note: The specific heat of renal artery tissue is 3.3 J/(g∙°C).) A.1 °C B.3 °C C.10 °C D.30 °C
C.10 °C
A fluid is stirred until it becomes turbulent. After the stirring stops, the fluid gradually returns to its original static state. The turbulent flow does not continue indefinitely because: A.the fluid is incompressible. B.the kinetic energy in the flow is transferred to gravitational potential energy. C.the energy put into the flow by stirring is transferred by convection. D.the energy put into the flow by stirring is dissipated by the fluid's viscosity.
D.the energy put into the flow by stirring is dissipated by the fluid's viscosity.
A 0.3-kg object with half the density of human fatty tissue is placed in water. Ignoring the atmospheric pressure, what percentage of the mass will be submerged?
For a floating object, the fraction submerged is equal to the ratio of the object's density to the fluid's density: fraction submerged=ρobject/ρfluid The density of human fat is given in the passage as 0.9 kg/L, and the object's density is half this value; ρobject is 0.45 kg/L. Because the object is less dense than water (ρwater is 1 kg/L), the object will float at the surface and be partially submerged. Using these values, the fraction submerged is: (0.45 kg/L) / (1 kg/L)=0.45 Therefore, 45% of the object will be submerged.
Two protein samples are placed in an electrophoresis device. One protein sample contains mostly lysine whereas the other protein contains mostly aspartate. Would both samples accelerate toward the anode when the voltage source of the electrophoresis device is activated? A.No, because the lysine-rich protein is negatively charged and the aspartate-rich protein is positively charged B.No, because the lysine-rich protein is positively charged and the aspartate-rich protein is negatively charged C.Yes, because both proteins are negatively charged D.Yes, because both proteins are positively charged
In this question, the electrophoresis anode has a positive q and the cathode has a negative q. The aspartate-rich protein has a negative q and accelerates toward the anode (ie, opposite the direction of E). The lysine-rich protein has a positive q and accelerates toward the cathode. Therefore, both protein samples would not accelerate toward the anode because only the aspartate-rich protein is negatively charged
Determining balloon displacement from velocity and time
In this question, when the weather balloon reaches 20 km it moves horizontally with the wind, which according to Figure 1 has a speed of 40 m/s and is directed at 315°. therefore the balloon's displacement is 288 km at a direction of 315°.
Finding MAP for blood pressure
MAP= DP + (SP-DP)/3 from the figure the highest arterial pressure is 120 mmHg(SP) and the lowest is 90 mmHg(DP) MAP= 90mmHg + (120mmHg-90mmHg)/3 = 100 mmHg
What is the change in blood pressure over a 10 cm long section of the aorta? (Note: Viscosity of blood is η = 2 mPa∙s.)
Poiseuille's law describes fluid flow through a cylindrical pipe in terms of the volumetric flow rate, change in pressure, fluid viscosity, and physical dimensions of the pipe. The equation can be used to calculate the change in blood pressure over a specific length of the aorta
Pressure volume loop shows the pressure and volume in the heart during the cardiac cycle
Pressure volume loops from the right and left ventricles show similar stroke volumes but lower pressure in the right ventricle.
refractive indices of glass fiber and 2 lenses
Snell's law governs the refraction of light when crossing a boundary of two media with different refractive indices. Light traveling from a medium with a higher refractive index into one with a lower refractive index will have a refracted angle that is greater than the incident angle.
systolic vs diastolic pressures
Systolic pressure is the maximum measured blood pressure due to ventricular contraction, and diastolic pressure is the minimum measured blood pressure due to heart relaxation. The mean arterial pressure (MAP) is approximated from arterial systolic (SP) and diastolic (DP) pressures by MAP=DP+(SP−DP)/3
An individual that weighs 700 N in air has an apparent weight of 40 N when submerged in water. What is the volume of the displaced water?
The apparent weight of a submerged object is its reduced weight due to an upward buoyant force. The buoyant force is equal to the weight of the displaced fluid, which is the product of the fluid's density ρ, volume of displaced fluid V, and the gravitational acceleration g: FB = ρVg. Physics Subject 2. Fluids Foundation 4. Data-based Statistical Reasoning Skill
blood pressure drop in arterioles with 1 capillary network
The arterioles are responsible for reducing the blood pressure from the major arteries (high blood pressure) to the capillary networks (low blood pressure). As a result, the arterioles are the primary pressure-reducing vascular region of the circulatory system. Physics Subject 2. Fluids Foundation 3. Reasoning about the Design and Execution of Research Skill
Which group of blood vessels is the main source of peripheral resistance?
The arterioles because they experience the largest pressure drop In addition to having the greatest vascular resistance, the arterioles are also one of the main regulators of blood pressure. Unlike other vessels, the arterioles are very muscular and can significantly change their vessel radii. By constricting or relaxing, these vessels can change the total peripheral resistance to maintain blood pressures as necessary.
The diameter of a segment of an artery is reduced by a factor of two due to an obstruction. Assume that the flow is incompressible and laminar, and therefore follows the continuity equation. Compared to an unobstructed segment of the artery, the velocity of blood in the obstructed segment of the artery is: 4 times as large
The continuity equation expresses the conservation of mass observed as fluids flow through a conduit. The continuity equation indicates that velocity is inversely proportional to the square of diameter. Physics Subject 2. Fluids Foundation 2. Scientific Reasoning and Problem-solving Skill
For a constant current entering the body, relatively high body fat content would be indicated by:
The current entering and exiting a resistor remains the same because electric charge is always conserved. The voltage across a resistor is the product of resistance and current (V = IR). Therefore, tissues with a higher resistance will have a higher voltage across them for the same amount of current.
Assume the aorta is a straight, uniform pipe closed at one end. Which expression gives the fundamental resonant frequency (in Hz) for this pipe? (Note: Assume the speed of sound in air v = 360 m/s.)
The harmonic frequency in a pipe equals the ratio of the speed of sound and the harmonic wavelength. The fundamental harmonic wavelength of a pipe closed on one end is four times greater than the pipe's length.
Air parcels sink downward if work done by the buoyant force is negative
The sign of work depends on the alignment of the force and displacement vectors. When work is negative, displacement is opposite to the applied force.
Pulse pressure equals the difference between the systolic and diastolic blood pressure
The systolic pressure is the maximum blood pressure in the aorta, and the diastolic pressure is the minimum pressure in the aorta.
Blood flow in the aorta becomes turbulent at a Reynolds number of approximately 6,000. If the diameter of the aorta is approximately 2 cm, what is the average velocity of blood at this Reynolds number?
The transition from laminar to turbulent flow in a fluid is indicated by the Reynolds number Re of a flow
Effect of blood vessel radius on blood velocity
The volumetric flow rate of blood is constant in all the vascular regions of the kidney. The blood velocity equals the ratio of the volumetric flow rate and the blood vessel cross-sectional area. Physics Subject 2. Fluids Foundation 3. Reasoning about the Design and Execution of Research Skill
According to the figure, the gauge area A2 is half the LVAD area A1 ( A2 = A1/2).
Therefore, the force experienced by the force gauge is 1/2 the LVAD force, corresponding to a 1:2 ratio between the force at the force gauge and the force at the LVAD
An object with the same density as water is stationary and suspended in a container filled with water. A downward force is momentarily applied to the object. Assuming the water density remains constant and ignoring the effects of fluid friction, what will happen to the object immediately after this downward force is removed? A.The object will sink at a constant velocity. B.The object's downward velocity will increase with time. C.The object will quickly stop sinking. D.The object will sink before returning to its initial position.
When a mass experiences a net force, the mass will accelerate in the direction of the force (F = ma). When no net force acts on an object, its velocity remains unchanged. Therefore, an object will accelerate to a velocity when a force is applied and will continue at the same velocity after the force is removed.
Doppler shift can be approximated by the product of the frequency of the source and the ratio of the relative velocity and the speed of the wave in the medium
When the source and observer move toward each other, the relative velocity and the Doppler shift are positive.
Increasing temperature of ideal gas increase
average molecular kinetic energy
How will PP change if PS increases by 10% and PD increases by 20%?
decrease by 10%
The venturi effect
describes the decreased pressure associated with increased velocity of a fluid flowing in a pipe. This effect derives from a special case of Bernoulli's equation, in which the height of the fluid remains constant.
The advantage of using gamma rays for tumor therapy over x-rays is that gamma rays:
have higher energy
Decreasing anode/cathode distances does what
increases acceleration of samples
Blood cells in the aorta experience an ultrasound signal that is shifted +3000 Hz relative to the original signal transmitted from the Doppler velocity sensor. Which of the following best describes the aortic blood velocity in this situation? (Note: Assume speed of sound in the blood is c = 1500 m/s.)
it is moving toward the doppler velocity sensory at its maximum velocity
Which graph depicts the flow with the largest turbulent kinetic energy?
larger humps means larger spread and greater standard deviation
Finding volumetric flow rate when given frequency of 1.5 Hz
stroke volume= 120mL-50mL= 70 mL 1.5 HZ--> cycles/min (1.5 cycles/1s) (60s/1min)= 90 cycles/min (beats per min) 70mL x 90/min= 6300 mL/min
Pulse wave velocity is equal to
the product of the frequency and the wavelength. When the frequency is constant, changed in the pulse wave velocity cause a proportional change in the wavelength
The area enclosed by the cardiac PV loop is
the work done
A way to increase the transfer of heat from the body to the environment would be
to increase the respiration rate
The hydrostatic weighing container above is filled with water to a depth of 2 m. If point A is 0.7 m above the bottom of the container, what is the pressure due to the weight of the water at point A? (Note: The density of water is 1,000 kg/m3.)
1.3x10^4 N/m^2
Mass flow rate when given: blood flows at avg. velocity of 10cm/s radius of blood vessel= 0.2 cm and each 1cm^3 of blood volume contains 1mg of dissolved glucose
1.3 mg of glucose passes by a segment of artery each second
