AS & A Level Physics - 9702 Paper 1 2020 Summer Zone 2

What is a reasonable estimate of the mass of a raindrop?

Which quantity is a scalar?

A galvanometer of resistance 5\(\Omega\) is to be used in a null method.
In order to protect the galvanometer from damage due to an excessive initial current, resistors of resistance 0.5\(\Omega\) and 1 k\(\Omega\) are available.
Which arrangement would provide this protection?

Readings are made of the current $I$ for different voltages $V$ across a fixed resistor. The results are plotted on a graph to show the variation of $I$ with $V$.

What is the best description of the errors in the readings? 

A stone is dropped from a height of 20 m above water. The graph shows the variation with time of the velocity of the stone.

Which statement describes the approximate position of the stone four seconds after it is dropped? 

A car X is travelling at a constant speed $u$ along a straight road. At time $t = 0$ a second car Y is a distance $d_0$ behind car X and travelling at a speed $v$ in the same direction.

Speed $v$ is less than speed $u$. At time $t = 0$ car Y begins to accelerate with a constant acceleration. Car Y overtakes car X at time $t = T$.

Which graph could best show the variation with time $t$ of the distance $d$ between the cars?

The resultant force acting on an object is slowly increased.

Which graph could show the variation with time $t$ of the momentum $p$ of the object? 

An astronaut has a weight of 660 N when she is standing on the Earth's surface.

The acceleration of free fall on the surface of Mars is $3.71 \, \text{m/s}^2$.

What would be the weight of the astronaut if she stood on the surface of Mars?

A mass $m_1$ travelling with speed $u_1$ collides with a mass $m_2$ travelling with speed $u_2$ in the same direction. After the collision, mass $m_1$ has speed $v_1$ and mass $m_2$ has speed $v_2$ in the same direction. The collision is perfectly elastic.

Which equation is not correct? 

The diagrams show a negative electric charge situated in a uniform electric field and a mass situated in a uniform gravitational field.

Which row shows the directions of the forces acting on the charge and on the mass? 

A bicycle pedal is connected to a pivot by a metal bar, as shown.

The force on the pedal is 60 N downwards.

What is the moment of this force about the pivot? 

A thin horizontal beam XY is freely hinged at point Y to a vertical wall. The beam is held stationary by a cable XZ which is attached to the wall at point Z.

The beam supports a weight $W$ at point X. The forces in the cable and the beam are $F_C$ and $F_B$ respectively.

Which vector triangle represents the forces acting on point X? 

A pipe, open at one end, floats in a liquid as shown.

The cross-sectional area of the pipe is 0.012 m². The weight of the pipe is 32 N.

What is the density of the liquid? 

During an interval of time, fuel supplies energy X to a car.

Some of this energy is converted into kinetic energy as the car accelerates.

The rest of the energy Y is lost as thermal energy.

What is the efficiency of the car?

In which situation is work done on an object?

A spring is attached at one end to a fixed point. A mass is then hung from the other end of the spring. The spring has extension $x$ when the system is in equilibrium.

The variation of the tension in the spring with its extension is shown on the graph.

Which statement is correct? 

An escalator in an underground station has 25 people standing on it and is moving with a speed of $4.3 \, \text{ms}^{-1}$. The average mass of a person is 78kg and the angle of the escalator to the horizontal is $40^\circ$.

What is the minimum power required to lift these people?

An elastic cord of unstretched total length 16.0 cm and cross-sectional area $2.0 \times 10^{-6}\, \text{m}^2$ is held horizontally by two smooth pins a distance 8.0 cm apart.

The cord obeys Hooke’s law. A load of mass 0.40 kg is suspended centrally on the cord. The angle between the two sides of the cord supporting the load is $60^\circ$.

What is the Young modulus of the cord material? 

A student is investigating the mechanical properties of a metal. He applies different loads to a long thin wire up to its breaking point, and measures the extension of the wire for each load. He then plots a graph of stress against strain.

The student repeats the experiment with a wire made from the same metal, with twice the original length and half the diameter.'

Which graph is obtained?

Which statement describes what is meant by the plastic deformation of a material?

A transverse wave is moving along a rope. Two points X and Y on the rope are a quarter of a wavelength apart from each other.

Which statement is not possible for the two points X and Y at any instant?

Two progressive waves meet at a fixed point P. The variation with time of the displacement of each wave at point P is shown in the graph.

What is the phase difference between the two waves at point P? 

A microphone connected to the Y-plates of a cathode-ray oscilloscope (CRO) is placed in front of a loudspeaker. The trace on the screen of the CRO is shown.

The time-base setting is 0.5 ms cm$^{-1}$ and the Y-plate sensitivity is 0.2 mV cm$^{-1}$.

What is the frequency of the sound from the loudspeaker and what is the amplitude of the trace on the CRO?

The diagram shows an experiment to produce a stationary wave in an air column. A tuning fork, placed above the column, vibrates and produces a sound wave. The length of the air column can be varied by altering the volume of the water in the tube.

The tube is filled and then water is allowed to run out of it. The first two stationary waves occur when the air column lengths are 0.14 m and 0.42 m.

What is the wavelength of the sound wave?

A stationary person measures the speed and wavelength of the sound from a horn on a stationary vehicle. The person then repeats the measurements when the vehicle is approaching at a constant speed.

Which row describes the measured wavelength and the measured speed of the sound wave from the moving vehicle when compared with the sound wave from the stationary vehicle?

The table shows the wavelengths of five electromagnetic waves.

Which is correctly identifies the principal radiation for each of these wavelengths?

Two progressive waves meet at a point.

Which condition must be met for superposition of the waves to occur?

A hill separates a television (TV) transmitter from a house. The transmitter cannot be seen from the house. However, the house has good TV reception.

By which wave effect at the hill could the TV signal reach the house? 

The diagram shows an arrangement for demonstrating two-source interference using coherent light of a single wavelength \( \lambda \).

An interference pattern is observed on a screen 3.0 m away from the slits X and Y, which have a separation of 1.0 mm.

The central bright fringe is at Q, and the second bright fringe from the centre is at P.

What is the distance between Q and P?

Light of wavelength $\lambda$ is incident normally on a diffraction grating. The angle between the second-order maximum and the normal to the grating is $\theta$. The variation with $\sin \theta$ of $\lambda$ is shown on the graph.

How many lines per millimetre are on the diffraction grating?

A dipole is a pair of charges of equal magnitude, one negative and one positive. The electric field of a dipole is shown below.

In which direction does the force act on an electron when at point X? 

A charged oil droplet of mass $m$ is falling, initially freely, in a vacuum between two horizontal metal plates that are separated by a distance $x$.

A potential difference (p.d.) $V$ is then applied across the plates. This results in the oil droplet continuing to accelerate downwards but with a reduced acceleration $a$.

The polarity of the applied p.d. is then reversed so that the direction of the electric force on the droplet is reversed. This results in the downwards acceleration of the oil droplet increasing to $3a$.

What is the magnitude of the charge on the oil droplet?

The number density of free electrons in copper is $8.0 \times 10^{28} \text{ m}^{-3}$. A copper wire has diameter 0.42 mm. What is the average drift speed of the free electrons in the wire when the current in the wire is 0.57 A?

An electric kettle is rated at 2.0 kW, which describes the power supplied to the heating coil in the kettle.
The coil has a resistance of 5.0 k\Omega.
What is the current in the coil?

A conductor consists of three wires connected in series. The wires are all made of the same metal but have different cross-sectional areas. There is a current $I$ in the conductor.
![conductor diagram]
Point $Y$ on the conductor is at zero potential.
Which graph best shows the variation of potential $V$ with distance along the conductor?

A cell of electromotive force (e.m.f.) $E$ and internal resistance $0.50\,\Omega$ is connected to a resistor of resistance $4.7\,\Omega$.

The maximum power that can be dissipated by the resistor without overheating is $0.50\,W$.
What is the maximum value of $E$ for the resistor not to overheat?

Kirchhoff's first and second laws link to the conservation of physical quantities. Which quantities do they link to? [Table_1]

In the circuit shown, X is a variable resistor whose resistance can be changed from 5.0Ω to 500Ω. The electromotive force (e.m.f.) of the battery is 12.0V. It has negligible internal resistance.

What is the maximum range of values of potential difference across the output?

An unstable nucleus goes through successive decays to become a final, stable nucleus. The initial nucleus and the final nucleus are isotopes of each other. How many $\alpha$ and $\beta^-$ particles could have been emitted during the decay sequence? [Table_1]

A hadron has a charge of $-e$ and is composed of three quarks.
What could be the quark composition of the hadron?