When a body is accelerating, the resultant force acting on it is equal to its

Transcription

1 When a body is accelerating, the resultant force acting on it is equal to its A. change of momentum. B. rate of change of momentum. C. acceleration per unit of mass. D. rate of change of kinetic energy.

2 In an experiment to measure the acceleration of free fall at the surface of the Earth, the following results were obtained. Acceleration of free fall / m s These results are A. accurate and precise. B. inaccurate but precise. C. accurate but imprecise. D. inaccurate and imprecise..

3 When a voltage V of 12.2 V is applied to a DC motor, the current I in the motor is 0.20 A. Which one of the following is the output power VI of the motor given to the correct appropriate number of significant digits? A. 2 W B. 2.4 W C W D W

4 Light is incident on a clean metal surface in a vacuum. The frequency maximum kinetic intercept energy = KE 4.8 max of 10the 14 Hz; electrons ejected from therefore surface minimum is measured energy for different = hf; values of the frequency f = of 4.8 the (±0.2) incident light The 6.9 measurements (±0.3) are shown plotted below. = 3.3 (±0.5) J; Use the graph to determine the minimum energy required to eject an electron from the surface of the metal (the work function).

5 A wave generator produces a power per unit length of 4.0 kw m 1 for waves of amplitude A and speed v. The efficiency of the generator is constant. The power per unit length obtained from waves of amplitude 2A and speed 2v would be A. 8.0 kw m 1. B. 16 kw m 1. C. 32 kw m 1. D. 64 kw m 1.

6 Some of the energy levels of the hydrogen atom are shown below ev 0.85 ev 1.51 ev 3.39 ev 13.6 ev Electrons are excited to the 0.85 ev level. How many different photon frequencies will be observed in the emission spectrum of hydrogen? A. 3 B. 4 C. 5 D. 6

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8 Raoul suggests that power losses in a transformer may be reduced by the following: I. Constructing the core from a solid block of steel. II. Using large diameter wire in the coils. III. Using wire of low resistivity. Which of the above suggestions would reduce power loss? A. I only B. II only C. II and III only D. I, II and III

9 Which one of the following is a correct definition of the decay constant of a radio-isotope? A. The constant of proportionality linking halflife to rate of decay of nuclei. B. The constant of proportionality linking decay rate to number of undecayed nuclei. C. The reciprocal of the half-life of the radioisotope. D. The rate of decay of nuclei in a fresh sample of the radio-isotope.

10 The number of heartbeats of a person at rest in one hour, to the nearest order of magnitude is A B C D

11 Outline two preventable mistakes that contributed to the nuclear disaster at the Fukushima Daiichi nuclear power plant in March, Diesel generators were placed near sea-level/sea wall was too low to prevent tsunami wave from entering the plant/sea water could have been used much earlier to cool the reactor/the Japanese government was slow to alert the public about the need for evacuation;

12 A ball is released from rest near the surface of the Moon. Which one of the following quantities increases at a constant rate? A. Only distance fallen B. Only speed C. Only speed and distance fallen D. Only speed and acceleration

13 A. G -1 B. G C. I P (V P ) -1 D. V P (I P ) -1

14 When the isotope aluminium-27 is bombarded with alpha particles, the following nuclear reaction can take place He Al X 2 13 Proton number Nucleon number A B C D neutron Which of the following correctly gives the atomic (proton) number and mass (nucleon) number of the nucleus X?

15 An object is moving at constant velocity. Which one of the following quantities must have zero magnitude? A. Weight of object B. Momentum of object C. Kinetic energy of object D. Resultant force on object

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17 Water is contained in a tidal basin behind a dam. The water has a depth h at high tide and zero at low tide, as shown in the diagram. The gravitational potential energy of the water stored in the basin between a high tide and a low tide is proportional to A. h. B. h. C. h 2. D. h 3.

18 A dry cell has an emf E and internal resistance r and is connected to an external circuit. There is a current I in the circuit when the potential difference across the terminals of the cell is V. State expressions, in terms of E, V, r and I where appropriate, for (i) the total power supplied by the cell; (ii) the power dissipated in the cell; (iii) the power dissipated in the external circuit.

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20 Two lengths, a and b, are measured to be 51±1 cm and 49±1 cm respectively. In which of the following quantities is the percentage uncertainty the largest? A. a + b B. a b C. a b D. a b

21 A coil of area S has N turns of wire. It is placed in a uniform magnetic field of strength B so that its plane makes an angle h with the direction of the magnetic field as shown. The magnetic flux linkage is A. BSN sin h. B. BSN cos h. C. BSN tan h. D. BSN.

22 The maximum electrical power generated by a wind turbine, P out, was measured over a range of incident wind speeds, v in. The graph below shows the variation with v in of P out. Uncertainties for the data are not shown. It is suggested that P out is proportional to v in. State one reason why the best fit line does not support this hypothesis. shape of curve wrong / curve does not go through zero;

23 The reading on the voltmeter is A. 2.0 V. B. 3.0 V. C. 4.0 V. D. 6.0 V.

24 Outline two advantages and two disadvantages of using wind turbines to generate electrical energy. advantages: wind is renewable so no resources used up / wind is free / no chemical pollution / carbon dioxide emission / does not add to the enhanced greenhouse effect; disadvantages: expensive initial / capital costs / large land area needed / visual / noise pollution / winds unpredictable / not constant / affect on birds;

25 The following are statements concerning radioactive decay. I. Alpha particles have discrete energies. II. The beta-energy spectrum is a broad continuous distribution of energies. III. Gamma rays are emitted with discrete energies. Which statement(s) is(are) evidence for the existence of nuclear energy levels? A. I only B. II only C. III only D. I and III only

26 The purpose of a nuclear power station is to produce electrical energy from nuclear energy. The diagram below is a representation of the principal components of a nuclear reactor pile used in a certain type of nuclear power station that uses uranium as a fuel. there is more uranium-238 present than uranium-235; neutron capture is more likely in U-238 with high energy neutrons; if the neutrons are slowed they are more likely to produce The function of the moderator is to slow down the fission in U-235 than neutron capture in U-238; neutrons produced in a reaction such as that described above. Explain why it is necessary to slow down the neutrons.

27 The purpose of a nuclear power station is to produce electrical energy from nuclear energy. The diagram below is a representation of the principal components of a nuclear reactor pile used in a certain type of nuclear power station that uses uranium as a fuel. The function of the moderator is to slow down the neutrons produced in a reaction such as that described control above. rate at which reactions take place; by absorbing neutrons; Explain the function of the control rods.

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29 (energy released) = x ( ) x 10 5 ; = MeV. [180 MeV]

30 In a mass spectrograph (spectrometer), ions of isotopes of the same element follow different semicircular paths in a uniform magnetic field as shown below. The difference in path curvature is essentially due to the fact that the ions have different values of A. charge only. B. mass only. C. mass and charge. D. mass and speed.

31 Determine the energy for one photon of the light J