Myanmar Matriculation: Physics (တက္ကသိုလ်ဝင်တန်း ရူပဗေဒ)

A flywheel accelerates uniformly from an angular velocity of 12 rad/s to 36 rad/s over a time interval of 8.0 s. What is its angular acceleration, and through what total angle does it rotate during this period?

• A3.0 rad/s² and 192 rad
• B3.0 rad/s² and 96 rad
• C6.0 rad/s² and 192 rad
• D2.4 rad/s² and 288 rad

A uniform solid disk of mass M = 4.0 kg and radius R = 0.50 m rotates about a fixed frictionless axis perpendicular to the disk through its center at an angular speed of 20 rad/s. What is the rotational kinetic energy of the disk?

• A50 J
• B100 J
• C200 J
• D400 J

A constant tangential force of 15 N is applied to the rim of a uniform solid cylinder of mass 6.0 kg and radius 0.40 m, pivoted on frictionless bearings along its central longitudinal axis. What is the resulting angular acceleration of the cylinder?

• A6.25 rad/s²
• B12.5 rad/s²
• C25.0 rad/s²
• D37.5 rad/s²

A figure skater spins with arms outstretched at an angular speed of 3.0 rad/s with a moment of inertia of 2.4 kg·m². When she pulls her arms inward, her moment of inertia decreases to 0.80 kg·m². Assuming zero net external torque, what is her new angular speed and by what factor does her rotational kinetic energy change?

• A9.0 rad/s; increases by a factor of 3
• B9.0 rad/s; remains unchanged
• C6.0 rad/s; increases by a factor of 2
• D1.0 rad/s; decreases by a factor of 3

A uniform solid sphere of mass M and radius R rolls without slipping down an inclined plane of inclination angle θ. What is the linear acceleration of its center of mass along the incline?

• A(1/2) g sin θ
• B(2/3) g sin θ
• C(5/7) g sin θ
• Dg sin θ

For an extended rigid body to remain in complete mechanical equilibrium, which condition(s) must be fulfilled?

• AThe net external force must be zero, but net torque can be non-zero
• BThe net external torque about any point must be zero, but net force can be non-zero
• CThe vector sum of all external forces must be zero and the vector sum of all external tor…
• DThe body must have constant non-zero angular momentum

A uniform horizontal beam of length 4.0 m and mass 30 kg is hinged to a vertical wall at one end and supported by a cable attached to its other end. The cable makes an angle of 30° above the horizontal beam. Taking g = 9.8 m/s², what is the tension in the cable?

• A147 N
• B294 N
• C588 N
• D339 N

Which physical modulus is defined as the ratio of tensile (or compressive) stress to longitudinal strain within the proportional limit of an elastic material?

• AShear modulus (modulus of rigidity)
• BYoung's modulus
• CBulk modulus
• DPoisson's ratio

A steel wire of length 2.0 m and cross-sectional area 2.0 × 10^-6 m² is stretched by a suspended load of 400 N. If Young's modulus for steel is 2.0 × 10^11 N/m², what is the elongation of the wire?

• A0.50 mm
• B1.0 mm
• C2.0 mm
• D4.0 mm

A metal wire of length L and cross-sectional area A is stretched by an extension e within its proportional limit. Which expression correctly gives the elastic potential energy stored per unit volume (energy density) in the wire?

• AYoung's modulus * strain
• B1/2 * stress * strain
• Cstress * strain
• D1/2 * Young's modulus * strain

At what depth in freshwater (density ρ = 1.00 × 10^3 kg/m³) does the hydrostatic gauge pressure equal standard atmospheric pressure (1.01 × 10^5 Pa)? (Take g = 9.80 m/s²).

• A5.15 m
• B10.3 m
• C14.7 m
• D20.6 m

In a hydraulic car lift, a small input piston of area 0.020 m² is hydraulically coupled to a large output piston of area 0.80 m². What minimum force must be exerted on the small piston to lift a vehicle weighing 16,000 N?

• A200 N
• B400 N
• C800 N
• D6400 N

A solid brass block of mass 4.2 kg and density 8400 kg/m³ is completely immersed in water of density 1000 kg/m³. Taking g = 9.8 m/s², what is the buoyant force acting on the block, and what is its apparent weight in water?

• ABuoyant force = 4.9 N; Apparent weight = 36.3 N
• BBuoyant force = 4.9 N; Apparent weight = 41.2 N
• CBuoyant force = 9.8 N; Apparent weight = 31.4 N
• DBuoyant force = 41.2 N; Apparent weight = 0 N

In an incompressible fluid undergoing steady, streamline flow along a pipe whose diameter is halved from d to d/2, what happens to the flow velocity?

• AIt halves
• BIt doubles
• CIt quadruples
• DIt increases eightfold

Water flows through a horizontal pipe of diameter 6.0 cm at a speed of 1.5 m/s. The pipe narrows to a constricted throat of diameter 2.0 cm. What is the speed of water in the constricted throat, and what is the volume flow rate through the pipe?

• Av2 = 4.5 m/s; Q = 1.41 × 10^-3 m³/s
• Bv2 = 13.5 m/s; Q = 4.24 × 10^-3 m³/s
• Cv2 = 27.0 m/s; Q = 8.48 × 10^-3 m³/s
• Dv2 = 1.5 m/s; Q = 4.24 × 10^-3 m³/s

A horizontal Venturi meter carries water (density ρ = 1000 kg/m³). The pipe cross-sectional area is A1 = 0.010 m² and the throat area is A2 = 0.0025 m². If the measured pressure difference between the main pipe and the throat is ΔP = P1 - P2 = 3000 Pa, what is the flow speed v1 in the main pipe?

• A0.63 m/s
• B1.26 m/s
• C2.53 m/s
• D0.40 m/s

An open large water tank develops a small leak hole at a depth of 4.9 m below the water surface. Assuming frictionless efflux and g = 9.8 m/s², what is the speed of efflux from the hole according to Torricelli's law?

• A4.9 m/s
• B7.0 m/s
• C9.8 m/s
• D19.6 m/s

How does Bernoulli's principle explain the aerodynamic lift generated by an aircraft wing (airfoil) in steady forward flight?

• AAir traveling faster over the curved upper surface creates lower pressure above the wing…
• BAir traveling faster over the upper surface increases the static pressure above the wing,…
• CThermal expansion of air beneath the wing creates strong convective upward currents
• DAir molecules bouncing off the lower surface compress the atmosphere to create Archimedea…

A liquid sample with an initial volume of 2.000 L is subjected to an increase in hydrostatic pressure of 5.0 × 10^6 Pa. If the bulk modulus of the liquid is 2.5 × 10^9 Pa, what is the decrease in its volume?

• A1.0 mL
• B2.0 mL
• C4.0 mL
• D8.0 mL

A square block of gelatin of base area 0.040 m² and height 0.050 m is anchored to a bench. A horizontal shear force of 1.2 N is applied uniformly across its top face. If the shear modulus of the gelatin is 600 Pa, what is the horizontal displacement (Δx) of the top surface?

• A1.2 mm
• B2.5 mm
• C5.0 mm
• D10.0 mm

A steel railway track has a length of exactly 25.00 m at a winter temperature of -5.0 °C. If the coefficient of linear expansion of steel is α = 1.2 × 10^-5 °C^-1, what is the increase in length of the track on a hot summer day at 35.0 °C?

• A6.0 mm
• B9.0 mm
• C12.0 mm
• D24.0 mm

An aluminum vessel of internal volume 500.0 cm³ is completely filled with glycerin at 20.0 °C. The volume expansion coefficient of glycerin is β_g = 5.0 × 10^-4 °C^-1 and the linear expansion coefficient of aluminum is α_al = 2.4 × 10^-5 °C^-1. How much glycerin overflows when the system is heated to 70.0 °C?

• A10.7 cm³
• B12.5 cm³
• C8.9 cm³
• D1.8 cm³

A glass window pane has an area of 1.5 m² and a thickness of 4.0 mm. The thermal conductivity of the glass is k = 0.80 W/(m·K). If the indoor temperature is 22.0 °C and outdoor temperature is 2.0 °C, what is the rate of heat conduction through the pane?

• A300 W
• B1200 W
• C6000 W
• D12000 W

Which mode of thermal energy transfer can take place across a perfect vacuum without requiring any intervening material medium?

• AThermal conduction
• BFree convection
• CForced convection
• DThermal radiation

A spherical blackbody radiator (emissivity e = 1.0) has a surface area of 0.20 m² and is maintained at an absolute temperature of 500 K. Taking the Stefan-Boltzmann constant as σ = 5.67 × 10^-8 W/(m²·K^4), what is the total thermal power radiated?

• A354 W
• B567 W
• C709 W
• D1418 W

An ideal gas sample occupies a volume of 4.0 L at an absolute pressure of 100 kPa and a temperature of 300 K. If the gas is compressed isothermally to a volume of 1.0 L, what is its new pressure?

• A25 kPa
• B100 kPa
• C200 kPa
• D400 kPa

What is the root-mean-square (rms) speed of oxygen molecules (O2, molar mass M = 0.032 kg/mol) at an absolute temperature of 300 K? (Take universal gas constant R = 8.314 J/(mol·K)).

• A242 m/s
• B395 m/s
• C484 m/s
• D521 m/s

In a thermodynamic process, a gas system absorbs 500 J of heat from its surroundings while expanding and performing 200 J of external work. What is the change in the internal energy of the system according to the First Law of Thermodynamics?

• A-700 J
• B-300 J
• C+300 J
• D+700 J

A sample of gas is kept at a constant pressure of 2.5 × 10^5 Pa while absorbing 1200 J of heat. During this isobaric expansion, its volume increases from 2.0 × 10^-3 m³ to 5.0 × 10^-3 m³. What is the work done by the gas and the change in its internal energy?

• AW = 750 J; ΔU = 450 J
• BW = 750 J; ΔU = 1950 J
• CW = 500 J; ΔU = 700 J
• DW = 1200 J; ΔU = 0 J

Two moles (n = 2.0 mol) of an ideal gas expand isothermally at T = 300 K from an initial volume V1 = 0.010 m³ to a final volume V2 = 0.0272 m³ (such that ln(V2/V1) = 1.00). Taking R = 8.31 J/(mol·K), what is the work done by the gas and the heat absorbed from the reservoir?

• AW = 0 J; Q = 0 J
• BW = 4990 J; Q = 4990 J
• CW = 4990 J; Q = 0 J
• DW = 2495 J; Q = 2495 J

During a reversible adiabatic expansion of an ideal monatomic gas (ratio of heat capacities γ = 5/3), its volume doubles (V2 = 2 V1). By what factor does its absolute temperature change?

• A0.50
• B0.63
• C1.00
• D1.59

On a pressure-volume (P-V) indicator diagram, what physical quantity is represented by the enclosed area of a closed cyclic loop?

• AThe total heat added to the system during the cycle
• BThe change in entropy over the entire cycle
• CThe net work done by (or on) the system during one complete cycle
• DThe maximum internal energy reached during the cycle

A cyclic heat engine executes a rectangular cycle on a P-V diagram with vertices A(1.0 × 10^5 Pa, 0.020 m³) -> B(3.0 × 10^5 Pa, 0.020 m³) -> C(3.0 × 10^5 Pa, 0.050 m³) -> D(1.0 × 10^5 Pa, 0.050 m³) -> A. What is the net work delivered by the engine per cycle?

• A3000 J
• B6000 J
• C9000 J
• D15000 J

For a cyclic heat engine, which option states the Kelvin-Planck form of the Second Law of Thermodynamics?

• AHeat cannot flow spontaneously from a cooler body to a hotter body
• BIt is impossible to construct a device operating in a cycle that absorbs heat from a sing…
• CThe total internal energy of an isolated system remains constant in all processes
• DAbsolute zero can be achieved in a finite sequence of thermodynamic operations

A heat engine absorbs 5000 J of heat from a hot reservoir each cycle and exhausts 3200 J of waste heat to a cold reservoir. What is the net mechanical work output per cycle and the thermal efficiency of the engine?

• AW = 1800 J; efficiency = 36%
• BW = 1800 J; efficiency = 56%
• CW = 3200 J; efficiency = 64%
• DW = 5000 J; efficiency = 100%

A Carnot heat engine operates between a hot thermal reservoir at 500 °C and a cold reservoir at 25 °C. What is the maximum theoretical efficiency of this Carnot engine?

• A95.0%
• B61.4%
• C38.6%
• D50.0%

Water flows through a hydroelectric station at 40 m^3/s and falls through a net head of 25 m. If the turbine-generator efficiency is 80%, what electrical power is produced? Use water density 1000 kg/m^3 and g = 9.8 m/s^2.

• A7.84 MW
• B9.80 MW
• C0.784 MW
• D78.4 MW

Which energy source is renewable because its usable supply is continually replenished by the Sun-driven water cycle?

• ACoal
• BHydroelectric power
• CNatural gas
• DUranium-235

A solar panel of area 12 m^2 receives irradiance of 750 W/m^2 and converts 18% of the incident energy to electricity. What electrical power does it deliver?

• A1.62 kW
• B9.00 kW
• C0.162 kW
• D50.0 kW

Which comparison best explains why replacing a coal-fired generator with wind turbines can reduce climate impact but does not make an energy system impact-free?

• AWind generation has no fuel-combustion carbon dioxide during operation, but construction,…
• BWind turbines create energy from nothing, so neither conservation of energy nor environme…
• CCoal and wind release identical operating emissions because all generators rotate
• DWind is non-renewable because every gust can be used only once

The speed of sound in dry air at 0 °C is 331 m/s. Using the standard linear approximation v ≈ 331 + 0.606 T (°C), what is the speed of sound in air at 25 °C?

• A331 m/s
• B346 m/s
• C356 m/s
• D371 m/s

A sound source emits acoustic waves uniformly in all directions. At a distance of 10.0 m, the detected sound intensity is 1.0 × 10^-4 W/m². Taking the reference threshold of hearing as I0 = 1.0 × 10^-12 W/m², what is the sound intensity level in decibels (dB)?

• A40 dB
• B80 dB
• C120 dB
• D160 dB

A police cruiser emits a siren sound at a frequency of 600 Hz while traveling at 30 m/s toward a stationary bystander. If the speed of sound in air is 330 m/s, what frequency is detected by the bystander?

• A545 Hz
• B600 Hz
• C660 Hz
• D720 Hz

A locomotive sounding a 450 Hz whistle approaches a station platform at 20 m/s. An alert passenger on the platform runs at 4.0 m/s toward the oncoming train. Taking the speed of sound in air as 340 m/s, what frequency does the passenger hear?

• A418 Hz
• B455 Hz
• C478 Hz
• D484 Hz

For an organ pipe of length L open at both ends, what is its fundamental resonant frequency (f_open), and how does it compare to the fundamental frequency (f_closed) of a pipe of identical length closed at one end? (Let v be sound speed).

• Af_open = v / (4L); it is half the frequency of the closed pipe
• Bf_open = v / (2L); it is twice the frequency of the closed pipe
• Cf_open = v / (2L); it is equal to the frequency of the closed pipe
• Df_open = v / L; it is four times the frequency of the closed pipe

A resonance tube closed at one end has a fundamental resonant frequency of 250 Hz in air (speed of sound v = 340 m/s). What is the effective length of the air column, and what is the frequency of its first overtone (next higher harmonic)?

• AL = 34 cm; first overtone = 500 Hz
• BL = 34 cm; first overtone = 750 Hz
• CL = 68 cm; first overtone = 500 Hz
• DL = 17 cm; first overtone = 750 Hz

Which set of conditions is necessary to produce a steady, well-defined interference fringe pattern from two optical light sources?

• AThe sources must emit light of different wavelengths with random, time-varying phase diff…
• BThe sources must be coherent (maintain a constant phase difference over time) and monochr…
• CThe sources must emit broad-spectrum white light from two separate incandescent filaments…
• DThe sources must have mutually orthogonal linear polarization states

In a Young's double-slit experiment, monochromatic light of wavelength λ = 600 nm illuminates two slits separated by d = 0.30 mm. The interference pattern is viewed on a screen placed at D = 1.5 m. What is the fringe width (spacing between adjacent bright fringes)?

• A0.75 mm
• B1.5 mm
• C3.0 mm
• D6.0 mm