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HL Paper 2

The ball is now displaced through a small distance x from the bottom of the bowl and is then released from rest.

M18/4/PHYSI/HP2/ENG/TZ2/01.d

The magnitude of the force on the ball towards the equilibrium position is given by

m g x R

where R is the radius of the bowl.

A small ball of mass m is moving in a horizontal circle on the inside surface of a frictionless hemispherical bowl.

M18/4/PHYSI/SP2/ENG/TZ2/01.a

The normal reaction force N makes an angle θ to the horizontal.

State the direction of the resultant force on the ball.

[1]
a.i.

On the diagram, construct an arrow of the correct length to represent the weight of the ball.

[2]
a.ii.

Show that the magnitude of the net force F on the ball is given by the following equation.

                                          F = m g tan θ

[3]
a.iii.

The radius of the bowl is 8.0 m and θ = 22°. Determine the speed of the ball.

[4]
b.

Outline whether this ball can move on a horizontal circular path of radius equal to the radius of the bowl.

[2]
c.

Outline why the ball will perform simple harmonic oscillations about the equilibrium position.

[1]
d.i.

Show that the period of oscillation of the ball is about 6 s.

[2]
d.ii.

The amplitude of oscillation is 0.12 m. On the axes, draw a graph to show the variation with time t of the velocity v of the ball during one period.

[3]
d.iii.

A second identical ball is placed at the bottom of the bowl and the first ball is displaced so that its height from the horizontal is equal to 8.0 m.

                                   M18/4/PHYSI/SP2/ENG/TZ2/01.d

The first ball is released and eventually strikes the second ball. The two balls remain in contact. Determine, in m, the maximum height reached by the two balls.

[3]
e.



A vertical wall carries a uniform positive charge on its surface. This produces a uniform horizontal electric field perpendicular to the wall. A small, positively-charged ball is suspended in equilibrium from the vertical wall by a thread of negligible mass.

The centre of the ball, still carrying a charge of 1.2 × 10−6 C, is now placed 0.40 m from a point charge Q. The charge on the ball acts as a point charge at the centre of the ball.

P is the point on the line joining the charges where the electric field strength is zero. The distance PQ is 0.22 m.

The charge per unit area on the surface of the wall is σ. It can be shown that the electric field strength E due to the charge on the wall is given by the equation

E=σ2ε0.

Demonstrate that the units of the quantities in this equation are consistent.

[2]
a.

The thread makes an angle of 30° with the vertical wall. The ball has a mass of 0.025 kg.

Determine the horizontal force that acts on the ball.

[3]
b.i.

The charge on the ball is 1.2 × 10−6 C. Determine σ.

[2]
b.ii.

The thread breaks. Explain the initial subsequent motion of the ball.

[3]
c.

Calculate the charge on Q. State your answer to an appropriate number of significant figures.

[3]
d.i.

Outline, without calculation, whether or not the electric potential at P is zero.

[2]
d.ii.



A pipe is open at both ends. A first-harmonic standing wave is set up in the pipe. The diagram shows the variation of displacement of air molecules in the pipe with distance along the pipe at time t = 0. The frequency of the first harmonic is f.

A transmitter of electromagnetic waves is next to a long straight vertical wall that acts as a plane mirror to the waves. An observer on a boat detects the waves both directly and as an image from the other side of the wall. The diagram shows one ray from the transmitter reflected at the wall and the position of the image.

Sketch, on the diagram, the variation of displacement of the air molecules with distance along the pipe when t 3 4 f .

[1]
a.i.

An air molecule is situated at point X in the pipe at t = 0. Describe the motion of this air molecule during one complete cycle of the standing wave beginning from t = 0.

[2]
a.ii.

The speed of sound c for longitudinal waves in air is given by

c = K ρ

where ρ is the density of the air and K is a constant.

A student measures f to be 120 Hz when the length of the pipe is 1.4 m. The density of the air in the pipe is 1.3 kg m–3. Determine the value of K for air. State your answer with the appropriate fundamental (SI) unit.

[4]
b.

Demonstrate, using a second ray, that the image appears to come from the position indicated.

[1]
c.i.

Outline why the observer detects a series of increases and decreases in the intensity of the received signal as the boat moves along the line XY.

[2]
c.ii.



A lighting system consists of two long metal rods with a potential difference maintained between them. Identical lamps can be connected between the rods as required.

The following data are available for the lamps when at their working temperature.

 

Lamp specifications                      24 V, 5.0 W

Power supply emf                         24 V

Power supply maximum current   8.0 A

Length of each rod                       12.5 m

Resistivity of rod metal                 7.2 × 10–7 Ω m

A step-down transformer is used to transfer energy to the two rods. The primary coil of this transformer is connected to an alternating mains supply that has an emf of root mean square (rms) magnitude 240 V. The transformer is 95 % efficient.

Each rod is to have a resistance no greater than 0.10 Ω. Calculate, in m, the minimum radius of each rod. Give your answer to an appropriate number of significant figures.

[3]
a.

Calculate the maximum number of lamps that can be connected between the rods. Neglect the resistance of the rods.

[2]
b.

One advantage of this system is that if one lamp fails then the other lamps in the circuit remain lit. Outline one other electrical advantage of this system compared to one in which the lamps are connected in series.

[1]
c.

Outline how eddy currents reduce transformer efficiency.

[2]
d.i.

Determine the peak current in the primary coil when operating with the maximum number of lamps.

[4]
d.ii.



A fixed horizontal coil is connected to an ideal voltmeter. A bar magnet is released from rest so that it falls vertically through the coil along the central axis of the coil.

The variation with time t of the emf induced in the coil is shown.

 

Write down the maximum magnitude of the rate of change of flux linked with the coil.

[1]
a.i.

State the fundamental SI unit for your answer to (a)(i).

[1]
a.ii.

Explain why the graph becomes negative.

[3]
b.i.

Part of the graph is above the t-axis and part is below. Outline why the areas between the t-axis and the curve for these two parts are likely to be the same.

[2]
b.ii.

Predict the changes to the graph when the magnet is dropped from a lower height above the coil.

[3]
c.



The table gives data for Jupiter and three of its moons, including the radius r of each object.

A spacecraft is to be sent from Io to infinity.

Calculate, for the surface of Io, the gravitational field strength gIo due to the mass of Io. State an appropriate unit for your answer.

[2]
a.

Show that the gravitational potential due to Jupiter at the orbit of Io gravitational potential due to Io at the surface of Io is about 80.

[2]
b.i.

Outline, using (b)(i), why it is not correct to use the equation 2G×mass of Ioradius of Io to calculate the speed required for the spacecraft to reach infinity from the surface of Io.

[1]
b.ii.

An engineer needs to move a space probe of mass 3600 kg from Ganymede to Callisto. Calculate the energy required to move the probe from the orbital radius of Ganymede to the orbital radius of Callisto. Ignore the mass of the moons in your calculation. 

[2]
c.



A student strikes a tennis ball that is initially at rest so that it leaves the racquet at a speed of 64 m s–1. The ball has a mass of 0.058 kg and the contact between the ball and the racquet lasts for 25 ms.

The student strikes the tennis ball at point P. The tennis ball is initially directed at an angle of 7.00° to the horizontal.

The following data are available.

Height of P = 2.80 m
Distance of student from net = 11.9 m
Height of net = 0.910 m
Initial speed of tennis ball = 64 m s-1

Calculate the average force exerted by the racquet on the ball.

[2]
ai.

Calculate the average power delivered to the ball during the impact.

[2]
aii.

Calculate the time it takes the tennis ball to reach the net.

[2]
bi.

Show that the tennis ball passes over the net.

[3]
bii.

Determine the speed of the tennis ball as it strikes the ground.

[2]
biii.

A student models the bounce of the tennis ball to predict the angle θ at which the ball leaves a surface of clay and a surface of grass.

The model assumes

• during contact with the surface the ball slides.
• the sliding time is the same for both surfaces.
• the sliding frictional force is greater for clay than grass.
• the normal reaction force is the same for both surfaces.

Predict for the student’s model, without calculation, whether θ is greater for a clay surface or for a grass surface.

[3]
c.



In an experiment a beam of electrons with energy 440 MeV are incident on oxygen-16 O816 nuclei. The variation with scattering angle of the relative intensity of the scattered electrons is shown.

Identify a property of electrons demonstrated by this experiment.

[1]
a.i.

Show that the energy E of each electron in the beam is about 7 × 10−11 J.

[1]
a.ii.

The de Broglie wavelength for an electron is given by hcE. Show that the diameter of an oxygen-16 nucleus is about 4 fm.

[3]
a.iii.

Estimate, using the result in (a)(iii), the volume of a tin-118 Sn50118 nucleus. State your answer to an appropriate number of significant figures.

[4]
b.