Learn Extracted exam questions A-Level Physics 9702 Physics June 2025 Question Paper 24
9702 Physics June 2025 Question Paper 24
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Define the moment of a force.
A trapdoor has a hinge at end A, as shown in Fig. 1.1.
The trapdoor has length $80 \text{ cm}$ and weight $75 \text{ N}$. The mass of the trapdoor is uniformly distributed along its length.
A force $F$ acts at right angles to the trapdoor at end B so that the trapdoor is held in equilibrium at an angle of $42^{\circ}$ to the horizontal.
State the principle of moments.
Calculate the component of the weight that is perpendicular to the trapdoor.
component of weight = \hrulefill N
Calculate the magnitude of the force $F$.
$F =$ \hrulefill N
An object of constant mass moves in a straight line. The variation with time $t$ of the momentum $p$ of the object is shown in Fig. 2.1.
Define momentum.
Calculate the change in momentum of the object from time $t = 0$ to $t = 12\text{ s}$.
change in momentum = \hrulefill $\text{kg}\,\text{m}\,\text{s}^{-1}$
Calculate the magnitude of the resultant force acting on the object.
force = \hrulefill $\text{N}$
Describe the variation of the speed of the object from time $t = 0$ to $t = 8.0\text{ s}$.
By reference to Fig. 2.1, explain why the resultant force acting on the object during the first $8.0\text{ s}$ of its motion cannot be due to air resistance.
At time $t = 0$ the displacement $d$ of the object is zero.
On Fig. 2.2, sketch the variation of $d$ with time $t$ from $t = 0$ to $t = 12\text{ s}$.
Numerical values of $d$ are not required.
The lower end of a vertical spring is fixed to a horizontal surface, as shown in Fig. 3.1.
The mass of the spring is negligible. A block of mass $5.5 \text{ kg}$ drops vertically onto the spring and is brought to rest as the spring is compressed.
The block has kinetic energy $110 \text{ J}$ as it makes contact with the spring.
Calculate the speed of the block as it makes contact with the spring.
speed = \hrulefill $\text{ms}^{-1}$
The gravitational potential energy of the block decreases by $20 \text{ J}$ as the spring is compressed to its maximum compression $x_0$.
Show that $x_0$ is $0.37 \text{ m}$.
Assume that, as the spring compresses, all of the energy lost by the block is converted into the elastic potential energy of the spring.
Use the data from \textbf{(a)} and \textbf{(b)} to determine the maximum elastic potential energy of the spring.
Show your working.
maximum elastic potential energy = \hrulefill $\text{J}$
The variation of the force $F$ acting on the spring with the compression $x$ of the spring is shown in Fig. 3.2.
Use the information in (b) and your answer in (c) to show that the maximum force $F_0$ exerted on the spring by the block is $700\text{ N}$.
Use the information in (d) to determine, for the instant that the block is first brought to rest by the spring, the magnitude of:
the resultant force acting on the block
resultant force = \hrulefill N
the acceleration of the block.
acceleration = \hrulefill $\text{ms}^{-2}$
A source oscillates with frequency $f$ to produce a progressive wave of wavelength $\lambda$. The source takes time $t$ to produce $n$ complete oscillations.
State what is meant by a progressive wave.
State expressions, in terms of some or all of $f$, $\lambda$ and $n$, for:
\begin{itemize} \item the distance moved by a wavefront in time $t$ \end{itemize}
distance = \hrulefill
\begin{itemize} \item time $t$. \end{itemize}
time $t$ = \hrulefill
Use your answers in (ii) to determine an expression for the speed $v$ of the wave in terms of $f$ and $\lambda$.
Two identical microwave sources X and Y emit waves in phase. The sources are separated by a distance of $30\text{ cm}$, as shown in Fig. 4.1.
Fig. 4.1 (not to scale)
The intensity of the microwaves is to be investigated at points P and Q. Line PQ is parallel to line XY. Distance XP is equal to distance YP. Distance YQ is $72\text{ cm}$ and angle XYQ is $90^{\circ}$. The wavelength of the microwaves is $4.0\text{ cm}$.
Calculate the frequency, in GHz, of the microwaves.
frequency = \hrulefill GHz
Show that the difference between the path lengths XQ and YQ is 6 cm.
State and explain what may be deduced about the intensity of the microwaves at point Q.
A microwave detector is positioned at P and connected to a cathode-ray oscilloscope (CRO). The controls of the CRO are adjusted so that a waveform is shown on the screen.
Describe the changes to the amplitude of the waveform as the detector is moved from P to Q.
(a) (i) State and explain the effect, if any, on the resistance of a filament wire in a lamp as the current in the wire decreases.
(i) State and explain the effect, if any, on the resistance of a filament wire in a lamp as the current in the wire decreases.
State and explain the effect, if any, on the resistance of a filament wire in a lamp as the current in the wire decreases.
On Fig. 5.1, sketch the $I-V$ characteristic of a filament lamp.
A battery of electromotive force (e.m.f.) $E$ and negligible internal resistance is connected in parallel with two filament lamps A and B, as shown in Fig. 5.2.
The current in the battery is $3.3\text{ A}$ and the current in lamp A is $1.5\text{ A}$. The power dissipated in lamp A is $18\text{ W}$.
Calculate the e.m.f. $E$ of the battery.
$E = \hrulefill \text{ V}$
The filament wire of lamp B has a cross-sectional area of $1.4 \times 10^{-9} \text{ m}^2$. The number of free (conduction) electrons per unit volume in the metal of the filament wire is $3.4 \times 10^{28} \text{ m}^{-3}$.
Calculate the average drift speed of the free electrons in the filament wire of lamp B.
average drift speed = \hrulefill $\text{ ms}^{-1}$
A battery of electromotive force (e.m.f.) $6.0\text{ V}$ and negligible internal resistance is connected in series with a variable resistor and a uniform resistance wire XY, as shown in Fig. 6.1.
Wire XY has length $2.00\text{ m}$ and resistance $8.0\text{ }\Omega$. The resistance $R$ of the variable resistor is adjusted so that the potential difference across wire XY is $2.4\text{ V}$.
Determine $R$.
$R = \hrulefill \Omega$
Explain why the potential difference $V$ between any two points on wire XY is proportional to the distance $L$ between those points.
A cell of e.m.f. $E$ and internal resistance $r$ is connected to the circuit, as shown in Fig. 6.2.
Resistance $R$ is unchanged. The movable connection P is positioned on wire XY so that the galvanometer reading is zero. Distance XP is $1.24 \text{ m}$.
Calculate $E$.
$E = \hrulefill \text{ V}$
The value of $R$ is now decreased.
State and explain the change that must be made to the position of P on wire XY so that the galvanometer reads zero again.
State the names of \textbf{two} different leptons.
- \hrulefill
- \hrulefill
In the following list, underline all the particles that are hadrons.
\begin{itemize} \item antineutrino \item beta-plus \item meson \item neutron \end{itemize}
By reference to quark composition, show that the charge of a proton is $+1.6 \times 10^{-19} \text{ C}$.