Physics

The simplified model below shows the reactants and products of a proton–antiproton reaction which produces three particles called pions, each having a different charge.

There are no other products in this process, which involves only the rearrangement of quarks. No electromagnetic radiation is produced. Assume that the initial kinetic energy of the proton and antiproton is negligible.

Protons consist of two up quarks ($u$) and a down quark ($d$). Antiprotons consist of two up antiquarks ($\bar{u}$) and a down antiquark ($\bar{d}$). Each of the pions consists of two quarks.

The following tables provide information about hadrons and quarks.

Table 1: Hadron information

Table 2: Quark charges

(c) Calculation of the pions’ velocities using classical physics predicts that each pion has a velocity, relative to the point at which the proton–antiproton reaction occurred, which exceeds $3 \times 10^8\ \mathrm{m\,s^{-1}}$.

Explain the problem with this prediction and how it can be resolved.

Two horizontal metal rods, A and B, of different materials are resting on a frictionless table. Initially they are at rest in position 1.
Both rods are then connected to a battery using wires. After the switch is turned on, currents of different magnitude flow in each rod. The rods move to position 2 after time, t. In position 2, B has a larger displacement than A from position 1. The masses of the wires are negligible.

Position 1 is reproduced below. Draw wires to show how the battery must be connected to the ends of the two rods in order for the magnitude of the current in each rod to be different, and for position 2 to be reached. No components, other than the wires, are required.

Two horizontal metal rods, A and B, of different materials are resting on a frictionless table. Initially they are at rest in position 1. Both rods are then connected to a battery using wires. After the switch is turned on, currents of different magnitude flow in each rod. The rods move to position 2 after time, t. In position 2, B has a larger displacement than A from position 1. The masses of the wires are negligible.
When the switch is turned on, the current in rod A is greater than the current in rod B.
Consider this statement.
Position 2 results from the larger current in rod A, causing a larger force to act on rod B.
Evaluate this statement with reference to relevant physics principles.

Many scientists have performed experiments to explore the interaction of light and matter.

Analyse how evidence from at least THREE such experiments has contributed to our understanding of physics.

A magnet is swinging as a pendulum. Close below it is an aluminium (non-ferromagnetic) can. The can is free to spin around a fixed axis as shown.

Analyse the motion and energy transformations of both the can and the magnet.

The Standard Model of matter states that protons are not considered to be fundamental particles because:
(A) protons may spontaneously decay into other particles.
(B) fundamental particles have no charge.
(C) protons can be broken apart in particle accelerators.
(D) protons are a member of the boson family of particles.

A tennis player launches a tennis ball vertically upwards. At time $T$, the tennis player catches the ball when it returns to its starting position.

Which of the following graphs shows the tennis ball’s velocity over time?

Students plotted the radiation of stars against their wavelengths.

If a star has a surface temperature of $4000\ \mathrm{K}$, what is the maximum wavelength of the radiation emitted by the star?
(A) $0.725 \times 10^{-7}\ \mathrm{m}$
(B) $7.25 \times 10^{-6}\ \mathrm{m}$
(C) $725 \times 10^{-7}\ \mathrm{m}$
(D) $725\ \mathrm{nm}$

Which of the following statements is true regarding the observations of two people, one travelling at $99.9\%$ of the speed of light, and one stationary?
(A) Both people will observe time to be passing at the normal rate in their frame of reference.
(B) The person travelling at $99.9\%$ of the speed of light will observe their time to be passing slower.
(C) The stationary person will observe their time to be passing slower.
(D) Both people will observe time to be passing slower in their frame of reference.

Which of the following statements about AC induction motors is correct?
(A) There is no current produced in induction motors.
(B) Induction motors need slip rings to operate.
(C) The magnetic field rotates faster than the rotor.
(D) The rotor rotates faster than the magnetic field.

A muon is an elementary particle similar to the electron, with an electric charge of $-1e$ but with a much greater mass. A muon and an electron are travelling at the same speed.

Which row gives the particle with the greater kinetic energy and the particle with the longer de Broglie wavelength?

In a Physics class, students conduct three experiments in which they observe various light sources through a spectroscope.

• Experiment 1 uses an incandescent lamp.
• Experiment 2 uses a sodium lamp.
• Experiment 3 uses an incandescent lamp and passes the light through sodium vapour.

Which row of the table identifies what the students would observe through the spectroscope in each experiment?

The diagram shows the perigee and apogee of the Moon—two points in the Moon’s elliptical orbit around Earth.

Which of the following statements is correct?
(A) When the Moon reaches the apogee, its gravitational potential energy as well as its kinetic energy will be at minimum. It will move at a low velocity.
(B) When the Moon reaches the apogee, its gravitational potential energy as well as its kinetic energy will be at maximum. It will move at a high velocity.
(C) When the Moon reaches the perigee, its gravitational potential energy will be at a minimum and its kinetic energy will be at a maximum. It will move at a high velocity.
(D) When the Moon reaches the perigee, its gravitational potential energy will be at a maximum and its kinetic energy will be at a minimum. It will move at a low velocity.

Two parallel plates separated by a distance $d$ have a potential difference $V$ across them. A particle with charge $Q$ is placed midway between the plates.

What is the magnitude of the electrostatic force acting on the particle?
(A) zero
(B) $\dfrac{QV}{2d}$
(C) $\dfrac{QV}{d}$
(D) $\dfrac{2QV}{d}$

$^{27}_{12}\mathrm{Mg}$ can decay by beta-minus emission to one of two possible excited states of $^{27}_{13}\mathrm{Al}$. Both excited states decay by emission of a gamma photon directly to the ground state.

The diagram below shows the energy levels and two routes for the beta decay.

One route results in the emission of a gamma photon with a higher frequency than the other photon.

What is the kinetic energy for the beta particle emitted in this route?
(A) $1.33\times10^{-13}\ \mathrm{J}$
(B) $1.63\times10^{-13}\ \mathrm{J}$ (C) (D)

A short copper rod $R$ is placed on a pair of thick horizontal parallel copper rails. A horizontal magnetic field exists in the direction shown by the dashed arrows. The diagram shows the apparatus when viewed from directly above.

When switch $S$ is closed, $R$ will tend to:
(A) Lift upwards away from the rails.
(B) Move to the left.
(C) Move to the right.
(D) Be pressed downwards onto the rails.

A transformer has 1000 windings on the primary coil and 200 windings on the secondary coil.
The primary voltage is $240\ \mathrm{V}$, with a primary current of $10.0\ \mathrm{A}$.
The secondary current is $44.0\ \mathrm{A}$.

What is the efficiency and type of this transformer?

For a planet orbiting a single star, which factors determine the planet’s orbital period?
(A) mass of planet; mass of star; radius of orbit
(B) mass of star; radius of orbit
(C) speed of planet; radius of orbit
(D) mass of star; mass of planet

An investigation was performed with the aim of measuring the value of the magnetic permeability constant, $\mu_0$.

Two wires, both of length $70.0\ \mathrm{cm}$, were arranged horizontally, with one wire above the other, as shown in the diagram below. The bottom wire is resting on an electronic balance.

When a current of $25.5\ \mathrm{A}$ flows through both wires, the reading on the electronic balance changes by $0.500\ \mathrm{g}$.

What is the value of $\mu_0$ as determined by this investigation?
(A) $3.4\times10^{-7}$
(B) $1.7\times10^{-7}$ (C) (D)

An investigation was performed with the aim of measuring the value of the magnetic permeability constant, $\mu_0$.

Two wires, both of length $70.0\ \mathrm{cm}$, were arranged horizontally, with one wire above the other, as shown in the diagram below. The bottom wire is resting on an electronic balance.

When a current of $25.5\ \mathrm{A}$ flows through both wires, the reading on the electronic balance changes by $0.500\ \mathrm{g}$.

Which measurement made in the above investigation has the greatest relative error?
(A) length of the wires
(B) separation of the wires
(C) current in wires
(D) change in the reading of the electronic balance

In the diagrams below the loops are initially all the same size and the magnetic field $B$ is the same.

In which situation would the average induced EMF around the loop be the greatest?
(A) S
(B) T
(C) U
(D) V

Which statement correctly matches Malus’ Law?
(A) The intensity of polarised light entering an analyser is directly proportional to the cosine squared of the angle between the polariser and the analyser.
(B) The intensity of polarised light entering an analyser is inversely proportional to the cosine squared of the angle between the polariser and the analyser.
(C) The intensity of non-polarised light entering an analyser is directly proportional to the cosine squared of the angle between the polariser and the analyser.
(D) The intensity of non-polarised light entering an analyser is inversely proportional to the cosine squared of the angle between the polariser and the analyser.

A rectangular coil has dimensions $3.0\ \mathrm{cm}\times4.0\ \mathrm{cm}$ and carries a current of $15.0\ \mathrm{mA}$ in a uniform magnetic field of $3.0\ \mathrm{T}$. The coil has 20 turns of wire and is free to rotate about the axis as shown.

If the coil is rotated by $25^\circ$, what is the torque acting on the coil?
(A) $9.79\times10^{-4}\ \mathrm{N\,m}$ clockwise
(B) $9.79\times {10}^{}$ anticlockwise (C) clockwise (D) anticlockwise

An engineer turns a nut by applying a constant force to a $25.00\ \mathrm{cm}$ spanner. They applied this force at different angles and measured the torque. The graph shows the data collected by the engineer.

What is the magnitude of the force applied to the nut?
(A) $14.8\ \mathrm{N}$
(B) $84.8\ \mathrm{N}$
(C) $339\ \mathrm{N}$
(D) $1333\ \mathrm{N}$