Biophysics Past Paper 2022-2023 (PHS1103) - Badr University

## Badr University in Assiut ### Final Exam **2022-2023, 1^st level** **School of Veterinary Medicine** **Biophysics for freshman students** **Date**: 23/8/2023 **Examiner**: Dr. Mohamed A. Sabet **Time allowed**: 2 hours **Code**: PHS1103 The exam is in 7 pages and consists of 2 quest...

## Badr University in Assiut ### Final Exam **2022-2023, 1^st level** **School of Veterinary Medicine** **Biophysics for freshman students** **Date**: 23/8/2023 **Examiner**: Dr. Mohamed A. Sabet **Time allowed**: 2 hours **Code**: PHS1103 The exam is in 7 pages and consists of 2 questions equivalent to 50 marks. **Answer all the following questions in the answer tables at the end.** **Choosing more than one answer is not allowed.** ### First question: True or False (23 marks, 1 mark each) 1. Time is measured in seconds in both F.P.S. and M.K.S. systems of units. 2. In general, for any element, higher the atomic mass, higher the density. 3. The dimensions of velocity are LT^-1 while for the momentum are MLT^-1. 4. All the vectors shown are equal. *[Image of four arrows pointing in different directions]*. 5. The body on the right in the shown figure (with smaller base of support) has more stability against toppling. *[Image of a triangle on top a rectangular prism with the apex pointing upwards. Another triangle is positioned on top of a larger rectangular prism with the apex pointing upwards. The center of gravity of the first triangle is denoted by "c.g." The center of gravity of the second triangle is denoted by "c.g."]*. 6. The muscles producing skeletal movements consist of thousands of parallel fibers. The thousands of fibers in each muscle result in a low variability of the muscle force. 7. The back-neck muscle movement represents a class 2 lever as shown in figure. *[Image of a human head with the bone structure showing the mechanism of the back-neck muscle movement]*. 8. Wavelength is the number of waves that pass a point in one second. 9. The period is the time needed to complete one vibration and is the reciprocal of the frequency. 10. Pitch is the perception of frequency while loudness is the perception of amplitude. 11. The speed of a sound wave decreases with decreasing the density of the material. So sound speed is generally highest in solids, medium in liquids, and slowest in gases. 12. Sound production is often associated with the respiratory system. The frequency of the sounds is determined by the tension on the vocal cords and the size of the larynx. 13. The speed of sound v is around 343 m/s at normal conditions, but this varies depending on temperature, humidity and medium. 14. The equation that determines the observed frequency f' by an observer with velocity v_o moving towards a stationary source, that emits a sound wave with a frequency f, $f' = f (\frac{v + v_o}{v})$. 15. If the bat is moving towards the reflector with a speed v_bat and the reflector (insect) is moving towards the bat with a speed v_reflector then the bat hears the echoes of his sound with a frequency f'' = f($\frac{v + v_{bat}}{v - v_{bat}}$)($\frac{v - v_{reflector}}{v + v_{reflector}}$). 16. Knowing that diesel is not soluble in water and using the data in the given table, water floats above diesel if mixed. | Compound | Density (Kg/m³) | |-------------------|------------------------| | Drilling mud | 1500-2000 | | Water | 1000 | | Diesel | 860 | | Gasoline | 725 | | Liquid Petroleum Gas (LPG) | 550 | | Liquefied Natural Gas (LNG) | 460 | 17. According to the previous table, the relative density of LPG is 5.5. 18. Pressure is measured in N/m³ or Pa. 19. If the force is kept constant, the applied pressure is inversely proportional to the area. 20. For incompressible ideal fluid, and according to the continuity equation, the velocity of the fluid is inversely proportional to the cross-sectional area of the pipe if the flow rate is kept constant. 21. Two of the turbulent flow reasons of blood are: when the rate of blood flow becomes too small or when it passes by an obstruction in a vessel. 22. The diastolic pressure represents the resistance to the blood flow in the blood vessels when the heart is more relaxed. 23. While monitoring the blood pressure, there is a noticeable effect of varying the arm position on the recorded blood pressure from the brachial artery. ### Second question: Choose the most accurate answer (27 marks, 1½ mark each). **1.** The ____ is assumed to be a basic quantity in physics a) Time b) Area c) Velocity d) Force **2.** The unit of the luminous intensity in the SI unit system is ... a) Steradian b) Candela c) Becquerel d) Ampere **3.** If the atomic mass of Fe is 56 g/mol, and Avogadro's number is assumed to be 6.02 x 10²³ atom/mol, the mass of Fe atom is ... a) 9.41 x 10²¹ g b) 10.60 × 10^-23 g c) 9.30 × 10^-23 g d) 1.08 x 10²² g **4.** The density of a solid sphere is 5.3 g/cm³, its density using the SI units is ... a) 5300 b) 0.53 c) 530 d) 5.3 **5.** If *A* = −10î + 3ĵ, *B* = 5î – 7ĵ, then *A* + *B* = ... a) -7î - 2ĵ b) -5î – 4ĵ c) -5î – 4ĵ d) 15î + 10ĵ **6.** If *A* = 3î – 4ĵ, its magnitude is ... a) -1 b) 1 c) 5 d) 7 **7.** If *Ā* = 10î + 7ĵ, its direction with respect to the positive x-axis is… a) 35° b) 125° c) -55° d) 145° **8.** If *Ả* = 2î + 2ĵ, *B* = 3î + 3ĵ, then *H* = *Ả*. *B* is ... a) 13 b) 12 c) 25 d) 36 **9.** For two vectors *A* and *B*, if |*A*|= 20 and |*B*|= 10 and the angle between the two vectors is 30°, then |*Ả* × *B*| = a) 173.2 b) 300 c) 100 d) 6000 **10.** The direction of the torque is perpendicular to the force and the force arm and is obtained by… a) The right-hand rule. b) The left-hand rule. c) The right-foot rule. d) The left-foot rule. **11.** The load is located between the applied force and the fulcrum in… a) Class 1 lever b) Class 2 lever c) Class 4 lever d) Class 3 lever **12.** A body is said to be in mechanical equilibrium if… a) Σ*F* = Στ b) Σ*F* ≠ Στ c) Σ*F* = Στ = 0 d) Only Σ*F* = 0 **13.** If the elbow contraction is assumed to be a lever, its mechanical advantage M is… a) Less than 1 b) Larger than 1 c) -1 d) 1 **14.** The height of a person whose center of gravity is at 100 cm, measured from the soles of his feet is around… a) 200 cm b) 179 cm c) 150 cm d) 56 cm **15.** The restoring torque T_w, due to the person's weight, against toppling, is ____ N.m if the mass of this person shown in figure is 100kg (assume the gravity g=10 m/s^2). *[Image of a man standing on a beam resting on a pivot point that is 0.1 m from the end of the beam. The center of gravity of the man is 1 m from the pivot point. the beam is 1.5 m long]*. **16.** If the applied force F_a, needed to make this person on the verge of toppling, is 80 N and the gravity g=10 m/s², then this person's mass is ____ kg. **17.** What force should the woman in the figure exert on the floor with each hand to do a push-up if her mass is 60 kg and the gravity is g=10 m/s²? Assume that she moves up at a constant speed. a) 294 N b) 180 N c) 147 N d) 360 N *[Image of a woman doing a push-up. Her center of gravity is labelled "CG". The distance from the woman's feet to the pivot point is 0.9 m. The distance from the woman's hands to the pivot point is 1.5 m]*. **18.** The human ear can hear sounds in the range of 20-20kHz, lower than 20 Hz, the waves are called ____, while higher than 20 kHz, the waves are called ____. a) ultrasound, infrasound b) sub-sound, super-sound c) infrasound, ultrasound d) super-sound, sub-sound **19.** If the frequency is f, the wavelength is λ, the wave number is k, and the angular frequency is ω, then the velocity of the wave is given by… a) v = fλ = ω/k b) v = λ/f = k/ω c) v = f/λ = ω/k d) v = λ/f = k/ω **20.** If the faintest sound that the human ear can hear is I_o = 10^-12 W/m², and the sound intensity of a truck horn is I = 10¹² W/m², then the sound intensity of this horn in decibels (dB) is… a) -240 b) 240 c) 24 d) -24 **21.** Suppose you're on a hot air balloon ride, carrying a buzzer that emits a sound of frequency f. If you accidentally drop the buzzer over the side while the balloon is rising at a constant speed, what can you conclude about the sound you hear as the buzzer falls toward the ground? a) The frequency and intensity increase. b) The frequency decreases and the intensity increases. c) The frequency decreases and the intensity decreases. d) The frequency remains the same, but the intensity decreases. **22.** What is the difference between the pressure at the bottom of a pool (assume water density is 1000 kg/m³, and gravity is 9.8) with a depth of 3 m and the atmospheric pressure? a) 2.9 × 10⁴ Pa b) 2.9 × 10⁵ Pa c) 9.2 × 10³ Pa d) 9.2 × 10⁵ Pa **23.** A sheet of paper has an area of about 10 m², the force on one side of this sheet of paper due to the atmospheric pressure (P_atm= 1×10⁵ N/m²) is... N a) 10^-6 b) 10⁶ c) 10^-4 d) 10⁴ **24.** Ideal fluid is characteristic with all the following properties except... a) Incompressible b) No smoke rings c) High viscosity d) The flow is steady; the fluid velocity is independent of time. **25.** If water flows through a pipe with the rate of 20 cm³/s, and the pipe radius is 2.5 cm, the velocity of the water is around... a) 1 m/s b) 3.2 m/s c) 8 m/s d) 392.5 m/s **26.** Pressure applied to an enclosed fluid is transmitted undiminished to every portion of the fluid and the walls of the containing vessel, this is known as... a) Bernoulli's principle b) Pascal's law c) Flow rate d) Archimedes' principle **27.** If the measured blood pressure for a patient is 70/40 mmHg, the patient is advised to... a) Use less salt b) Drink less water c) Lay down flat with raised legs d) Stand straight *** ### Answer sheet #### First question | | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | |---|---|---|---|---|---|---|---|---|---|---| | True | O | O | O | O | O | O | O | O | O | O | | False | O | O | O | O | O | O | O | O | O | O | | | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | |---|---|---|---|---|---|---|---|---|---|---| | True | O | O | O | O | O | O | O | O | O | O | | False | O | O | O | O | O | O | O | O | O | O | | | 21 | 22 | 23 | | | | | | | | |---|---|---|---|---|---|---|---|---|---|---| | True | O | O | O | | | | | | | | | False | O | O | O | | | | | | | | #### Second question | | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | |---|---|---|---|---|---|---|---|---|---|---| | a) | O | O | O | O | O | O | O | O | O | O | | b) | O | O | O | O | O | O | O | O | O | O | | c) | O | O | O | O | O | O | O | O | O | O | | d) | O | O | O | O | O | O | O | O | O | O | | | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | |---|---|---|---|---|---|---|---|---|---|---| | a) | O | O | O | O | O | O | O | O | O | O | | b) | O | O | O | O | O | O | O | O | O | O | | c) | O | O | O | O | O | O | O | O | O | O | | d) | O | O | O | O | O | O | O | O | O | O | | | 21 | 22 | 23 | 24 | 25 | 26 | 27 | | | | |---|---|---|---|---|---|---|---|---|---|---| | a) | O | O | O | O | O | O | O | | | | | b) | O | O | O | O | O | O | O | | | | | c) | O | O | O | O | O | O | O | | | | | d) | O | O | O | O | O | O | O | | | | *** **With my best wishes**