9702_w17_qp_23
A paper of Physics, 9702
Questions:
7
Year:
2017
Paper:
2
Variant:
3
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2
A liquid of density ρ fills a container to a depth h, as shown in . container liquid base area A h The base of the container has area A. Derive, from the definitions of pressure and density, the equation p = ρgh where p is the pressure exerted by the liquid on the base of the container and g is the acceleration of free fall. A small solid sphere falls with constant velocity through the liquid. State 1. the names of the three forces acting on the sphere, 2. a word equation that relates the magnitudes of these forces. State and explain the changes in energy that occur as the sphere falls. The liquid in the container is liquid L. Liquid M is now added to the container. The two liquids do not mix. The total depth of the liquids is 0.17 m. shows how the pressure p inside the liquids varies with height x above the base of the container. liquid L 9.25 9.20 9.15 9.10 0.05 0.10 0.15 0.20 liquid M p / 104 Pa x / m Use to state the value of atmospheric pressure, atmospheric pressure = Pa determine the density of liquid M. density = kg m–3
4. Forces, density and pressure  →  4.3. Density and pressure
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3
State the principle of conservation of momentum. Ball A moves with speed v along a horizontal frictionless surface towards a stationary ball B, as shown in . A B 4.0 kg 12 kg v before collision 4.0 kg 12 kg after collision initial path of ball A 30° A B θ 6.0 m s–1 3.5 m s–1 (not to scale) Ball A has mass 4.0 kg and ball B has mass 12 kg. The balls collide and then move apart as shown in . Ball A has velocity 6.0 m s–1 at an angle of θ to the direction of its initial path. Ball B has velocity 3.5 m s–1 at an angle of 30° to the direction of the initial path of ball A. By considering the components of momentum at right-angles to the direction of the initial path of ball A, calculate θ. θ = ° Use your answer in to show that the initial speed v of ball A is 12 m s–1. Explain your working. By calculation of kinetic energies, state and explain whether the collision is elastic or inelastic.
3. Dynamics  →  3.3. Linear momentum and its conservation
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4
By reference to the direction of propagation of energy, explain what is meant by a longitudinal wave. A car horn emits a sound wave of frequency 800 Hz. A microphone and a cathode-ray oscilloscope (c.r.o.) are used to analyse the sound wave. The waveform displayed on the c.r.o. screen is shown in . 1 cm 1 cm Determine the time-base setting, in s cm–1, of the c.r.o. time-base setting = s cm–1 The intensity I of the sound at a distance r from the car horn in is given by the expression I = k r 2 where k is a constant. shows the car in on a road. O Y X road 120 m 30 m An observer stands at point O. Initially the car is parked at point X which is 120 m away from point O. The car then moves directly towards the observer and stops at point Y, a distance of 30 m away from O. The car horn continuously emits sound when the car is moving between points X and Y. The sound wave at point O has amplitude AX when the car is at X and has amplitude AY when the car is at Y. Calculate the ratio AY AX . ratio = When the car is parked at X, the frequency of the sound from the horn that is detected by the observer is 800 Hz. As the car moves from X to Y, the maximum change in the detected frequency is 16 Hz. The speed of the sound in air is 330 m s–1. Determine, to two significant figures, 1. the minimum wavelength of the sound detected by the observer, wavelength = m 2. the maximum speed of the car. speed = m s–1
7. Waves  →  7.1. Progressive waves
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5
Define electric field strength. Two parallel metal plates in a vacuum are separated by 0.045 m. A potential difference V is applied between the plates, as shown in . metal plate metal plate proton 0.045 m V – + A proton is initially at rest on the surface of the positive plate. The proton in the uniform electric field takes a time of 1.5 × 10–7 s to reach the negative plate. Show that the acceleration of the proton is 4.0 × 1012 m s–2. Calculate the electric force on the proton. force = N Use your answer in to determine 1. the electric field strength, field strength = N C–1 2. the potential difference V between the plates. V = V An α particle is now accelerated between the two metal plates in by the electric field. Calculate the ratio acceleration of α particle acceleration of proton . ratio =
18. Electric fields  →  18.2. Uniform electric fields
18. Electric fields  →  18.4. Electric field of a point charge
18. Electric fields  →  18.1. Electric fields and field lines
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6
A filament lamp is rated as 30 W, 120 V. A potential difference of 120 V is applied across the lamp. For the filament wire of the lamp, calculate the current, current = A the number of electrons passing a point in 3.0 hours. number = Show that the resistance of the filament wire is 480 Ω. The filament wire has an uncoiled length of 580 mm and is made of metal. The metal has resistivity 6.1 × 10–7 Ω m at the operating temperature of the lamp. Calculate the diameter of the wire. diameter = m The potential difference across the lamp is now reduced. State and explain the effect, if any, on the resistance of the filament wire.
9. Electricity  →  9.3. Resistance and resistivity
6. Deformation of solids  →  6.1. Stress and strain
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