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Questions and Answers
A car tyre lasts typically 40,000 km. Estimate the number of rotations it makes during its lifetime.
A car tyre lasts typically 40,000 km. Estimate the number of rotations it makes during its lifetime.
Wine can be produced in large vats, shaped as in Fig. 1. Which is the most suitable graph for pressure as a function of depth?
Wine can be produced in large vats, shaped as in Fig. 1. Which is the most suitable graph for pressure as a function of depth?
A steady sound of 165 Hz is produced by a loudspeaker at one end of a field and it is received 157 m away. By what fraction of a cycle (measured in degrees from 0 to 360°) is the received signal out of phase? The speed of sound in air is 330 m s−1.
A steady sound of 165 Hz is produced by a loudspeaker at one end of a field and it is received 157 m away. By what fraction of a cycle (measured in degrees from 0 to 360°) is the received signal out of phase? The speed of sound in air is 330 m s−1.
A girl standing on a cliff throws two balls, one up and one down, at the same speed. How do the final velocities of each compare as they hit the sea?
A girl standing on a cliff throws two balls, one up and one down, at the same speed. How do the final velocities of each compare as they hit the sea?
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What is the formula for the volume of a sphere?
What is the formula for the volume of a sphere?
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What is the terminal voltage of a dc power supply when it is on open circuit?
What is the terminal voltage of a dc power supply when it is on open circuit?
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What is the value of the elementary charge?
What is the value of the elementary charge?
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What constant is represented by 'c'?
What constant is represented by 'c'?
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The __________ of a sphere is calculated as 4πr².
The __________ of a sphere is calculated as 4πr².
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The relationship of pressure and volume for a gas is described by the equation PV = _____
The relationship of pressure and volume for a gas is described by the equation PV = _____
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What happens to a uniform rod when a force F is applied to it?
What happens to a uniform rod when a force F is applied to it?
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What is the formula for power in terms of force and velocity?
What is the formula for power in terms of force and velocity?
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Study Notes
Senior Physics Challenge (Year 12)
- The Senior Physics Challenge is a competition for Year 12 students.
- The exam is one hour long and has a total of 50 marks
- Students are allowed to use any standard calculator without symbolic algebra capability or programmable features in "exam mode".
- Students may use any public examination formula booklet.
- Scribbled or unclear working will not gain marks.
Physical Constants
- Speed of light in free space (c) = 3.00 × 10⁸ m s⁻¹
- Elementary charge (e) = 1.60 × 10⁻¹⁹ C
- Planck constant (h) = 6.63 × 10⁻³⁴ J s
- Mass of electron (me) = 9.11 × 10⁻³¹ kg
- Mass of proton (mp) = 1.67 × 10⁻²⁷ kg
- Acceleration of free fall at Earth’s surface (g) = 9.81 m s⁻²
- Avogadro constant (NA) = 6.02 × 10²³ mol⁻¹
- Radius of Earth (RE) = 6.37 × 10⁶ m
- Radius of Earth’s orbit (R0) = 1.496 × 10¹¹ m
Formulas
- T(K) = T(°C) + 273
- Volume of a sphere = (4/3)πr³
- Surface area of a sphere = 4πr²
- v² = u² + 2as
- v = u + at
- s = ut + (1/2)at²
- s = (1/2)(u + v)t
- E = hf
- R = (ρℓ)/A
- P = Fv
- P = E/t
- P = VI
- V = IR
- v = fλ
- P = ρgh
- (1/R) = (1/R₁) + (1/R₂)
- PV = const. = const.T
Question 1 - A Car Tyre
- A car tyre lasts typically 40 000 km.
- Estimate the number of rotations the tyre makes during its lifetime.
Question 2 - Pressure in a Wine Vat
- Wine is stored in large vats.
- The pressure in a wine vat is a function of depth.
- Identify the most suitable graph for this relationship.
Question 3 - Sound Phase Difference
- A loudspeaker produces a 165 Hz sound.
- The sound is received 157 m away.
- The speed of sound in air is 330 m s⁻¹.
- Determine the fraction of a cycle (in degrees) by which the received signal is out of phase.
Question 4 - Balls Thrown from a Cliff
- Two balls are thrown from a cliff, one upwards and one downwards at the same speed.
- Compare the final velocities of both balls as they hit the sea.
Question 5 - Centre of Mass
- A 34 cm long uniform straight rod is spinning and translating across a smooth horizontal surface.
- At one moment, the velocities of the ends of the rod are 2.6 m s⁻¹ and 4.2 m s⁻¹, perpendicular to the rod.
- Sketch the motion of the rod as it slides across the surface.
- Determine the speed an observer needs to fly over the rod to see only its rotational motion.
- Calculate the frequency of rotation.
- Determine the magnitude of the velocity of one end of the rod after a quarter rotation.
- A cable of mass m hangs between two fixed points A and B, forming a curve.
- A force F is applied to the center of the cable to straighten it.
- Locate the center of mass on the sketch of the cable hanging under its own weight.
- Explain any changes to the center of mass when the force is applied.
Question 6 - Rod and Wedge
- A rod of mass m₁ is constrained to move vertically down a smooth slope of a wedge of mass m₂ and angle θ.
- The wedge accelerates to the right.
- Determine a conclusion about the types of motion of the rod and wedge based on the constant forces acting on them.
- As the wedge slides at speed v and the rod slides down at speed u, mark the motion of the contact point P on the slope and the new contact point of the rod.
- Relate u, v, and θ.
- Write an energy equation for the system in terms of m₁, m₂, u, v, g, and h if the rod falls through height h.
- Derive an expression for the speed of the wedge v in terms of m₁, m₂, g, h, and θ.
- Calculate the fraction of GPE lost by the rod gained by the wedge if m₁ = m₂ and θ = 30°.
- Write down an expression for the speed of the rod u and its acceleration.
Question 7 - Bulldozer's Caterpillar Track
- A bulldozer moves on a caterpillar track with a driving wheel diameter of 1.0 m.
- The wheel rotates once in 0.84 s.
- Determine the speed of a piece of mud stuck to the top of the moving track relative to a person standing at the side.
Question 8 - Beams and Sphere
- Three beams AB, BC, and CD of lengths ℓ, 2ℓ, and ℓ respectively are connected by hinges at B and C.
- The beams rest on a sphere of radius 2ℓ with points A, D, and the middle point of BC in contact with the sphere.
- Sketch a diagram of the beams and sphere.
- Calculate the obtuse angle between beams AB and BC.
Question 9 - DC Power Supply
- A DC power supply has a terminal voltage of 5.00 V on open circuit.
- The voltage drops to 4.90 V when a 2.00 Ω resistor is connected across the terminals.
- Determine the internal resistance of the power supply using a simple emf and internal resistance model.
- Calculate the terminal voltage when the load resistor is reduced to 0.400 Ω.
- A constant current device draws 0.40 mA in a circuit with a moving coil voltmeter.
- The voltmeter draws 1.0 mA at full-scale deflection and reads 90 V on the 300 V range.
- Determine the voltage applied to the device with the voltmeter removed from the circuit.
Question 10 - Inflating a Balloon
- A spherical balloon is inflated by blowing air into it.
- The inflation process is described by the equation: Pin − Pout = 2C((r⁶)/(r₀⁶))((1 - (r₀/r))/(r))
- Pin is the pressure inside the balloon, Pout is the external atmospheric pressure, r₀ is the uninflated radius, r is the radius, and C is a constant.
- Determine the dimensions of C.
- Estimate the maximum value of Pin − Pout from the graph in pascals.
- Estimate the work done in blowing up the balloon to a radius of 6 cm using two regions on the graph.
- Determine the relationship between the uninflated radius r₀ and the radius at maximum pressure rp.
- Two balloons of unequal radii are joined by an open tube.
- Determine the final configuration of radii if the lower pressure balloon initially has a greater radius.
- State the condition under which the balloons would end up with equal radii if the lower pressure balloon initially has a lesser radius.
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Description
Test your knowledge in physics with the Senior Physics Challenge for Year 12 students. This one-hour exam assesses 50 marks of various physics concepts, utilizing physical constants and essential formulas. Prepare to solve problems and demonstrate your understanding of key physical principles.
