enwaecphysics2008

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1. If the air inside a rigid box is heated, the Average speed of the molecules increases Pressure of the air increases Average separation of the molecules increases Which of the statements above are correct? I and II only II and III only I and III only I, II and III 2. Which of the following sets of physical quantities is fundamental? Length, mass and time Speed, length and time Speed, mass and distance Distance, speed and time 3. The diagram above illustrates a Hare’s apparatus. e1, e2 represent densities and h1, h2 heights of columns of liquids. Which of the following equations is correct? h_1=(h_2 e_1)/e_2 h_1=(h_2 e_2)/e_1 h_1= (e_1 e_2)/h_2 h_1= e_1/(h_2 e_2 ) 4. Which of the following statements about Archimedes’ principle is correct? The upthrust on a body is a measure of the Mass of fluid displaced Weight of the body Volume of the body Weight of the fluid displaced 5. Which of the following is/are in random motion? Pollen grains in water The molecules of hydrogen gas Fine chalk particles floating in air I and II only I and III only II and III only I, II and III 6. A car travelling with a uniform velocity at 30 ms-1 along a horizontal road overcomes a constant frictional force of 600N. Calculate the power of the engine of the car. 18 kW 20 kW 180 kW 200 kW 7. A rectangular block of dimensions 2.0 m × 1.0 m × 0.5 m weighs 200N. Calculate the maximum pressure exerted by the block on a horizontal floor. 100 Nm-2 200 Nm-2 300 Nm-2 400 Nm-2 8. The diagram above represents the displacement-time graph of the motion of an object thrown upwards. The velocity of the object at the point P is Maximum Uniform Zero Terminal 9. A very sensitive spring balance was used to determine the weight of an object at the North Pole. When the same spring balance was used to measure the weight of the same object at the equator, it was forced to reduce. The explanation for this observation is that It is very hot at the equator The spring balance has expanded The acceleration of free fall due to gravity varies with location The mass of the body is reduced 10. A ship moving northward with speed Vs is acted upon by a wind blowing due west at a speed Vw. Which of the following diagrams correctly indicates the velocity VR of the wind relative to the ship?

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11. The diagram above shows three forces F1, F2 and F3 which keep the bar AB in horizontal equilibrium. Which of the following equations is correct? F3 =F1+F2 F2=F1+F2 F1=F2F3 F1 = F2+F3 12. The mass attached to a string is moving in a circular path. If the speed doubled, the tension in the string will be Doubled Halved Four times as great One-fourth as much 13. An object of mass 2 kg moving with a velocity of 3 ms-1collides head-on with another object of mass 1 kg moving in opposite direction with a velocity of 4 ms-1. If the objects stick together after collusion, calculate their common speed. 0.60 ms-1 0.67ms-1 2.00 ms-1 3.33 ms-1 14. Which of the following devices converts heat energy to electrical energy? Transformer Dynamo Thermocouple Thermostat 15. A ball is dropped and it hits the floor at a point A. It rebounds upwards to a point B. While moving from A to B its Kinetic energy is increasing Potential energy is increasing Potential energy is decreasing Kinetic energy remains constant 16. An object of mass 0.25 kg moves at a height h above the ground with a speed of 4 ms-1. If the mechanical energy at this height is 12 J, determine the value of h. [g=10 ms-1] 0.8 m 4.0 m 4.8 m 5.6 m 17. Which of the following equations for the efficiency of a machine is correct? Efficiency = (velocity ratio)/(mechanical advantage) 100% Efficiency = input/output ×100% Efficiency = (load distance)/(effort distacne)×100% Efficiency = (mechanical advantage)/(velocity ratio)× 100% 18. The design of the thermostat an electric iron is based on the Emission of electrons from metals when heated Increase in size of metals when heated Increase in the density of metals when heated Change in the mass of metals when heated 19. A metal rod of length 50 cm is heated from 40℃ to 80℃. If the linear expansivity of the material is α, calculate the increase in length of the rod (in metres) in terms of α. 20α 200α 2000α 20000α 20. The cubic expansivity of a certain gas at constant pressure is 1/273K-1. If a given mass of the gas is held at constant pressure and its volume at 0 ℃ is 273 m3, determine the volume of the gas at 273 ℃. 273 m3 546 m3 819 m3 1092 m3

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21. Water of mass 1.5 kg is heated from 30 ℃ to 80 ℃ using an electric kettle which is rated 5 A, 230V. Calculate the time taken to reach the final temperature. [Specific heat capacity of water =4200 Jkg-1K-1] 4.57 minutes 5.02 minutes 7.30 minutes 10.04 minutes 22. The working principle of a pressure cooker is based on the Increase in volume of steam inside it Complete trapping of heat inside it Increase in the pressure of the pot Decrease in the pressure of the pot 23. It takes a shorter time for a liquid to boil at the top of a mountain than at the base because at the top, the Temperature is higher Pressure is lower Humidity is higher Temperature is constant 24. Light is considered as a transverse wave because it travels Through materials without causing disturbance of the medium Through space with constant speed In a direction parallel to the plane containing the electric and magnetic fields In a direction perpendicular to the plane containing the electric and magnetic fields 25. The diagram above illustrates the sun, moon and earth in the same straight line during an eclipse. An observer at the point P on earth observes Annular eclipse Partial eclipse Total eclipse No eclipse 26. The letter F is placed in front of a plane mirror as illustrated in the diagram below Which of the following represents the image observed? 27. In the day time, it is possible to see under shady areas such as under a tree, because light has undergone Internal reflection Refraction Diffraction Diffuse reflection 28. The distance between a concave mirror and an object placed in front of it is 1.0 m. If the radius of curvature of the mirror is 4.0m, the image formed will be 2.00 m behind the mirror 2.00 m in front of the mirror 1.25 m in front of the mirror 1.25 m behind the mirror 29. The image of an object formed by a convex mirror is Real, erect and enlarged Real, inverted and enlarged Virtual, erect and diminished Virtual, erect and enlarged 30. When viewed straight down, a fish in a pond is Farther below than it appears to be Nearer than it appears to be Found at exactly the same spot it is seen Seen beside its image

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31. A converging lens and a screen are placed 20 cm and 80 cm respectively from an object in a straight line so that a sharp image of the object is 3 cm high, calculate the height of the image formed. 1 cm 9 cm 12 cm 15 cm 32. Which of the following defects of vision is as a result of the eye ball being too long? Long sight Astigmatism Short sight Loss of accommodation 33. A sound wave is produced from a source and an echo is heard t seconds afterwards. If d is the distance of the reflecting surface from the source, v the speed, p the wavelength and T the period of the wave, then d=2t/λ d=λt/2T d=2T/λt d=λT/2t 34. A negatively charged rod is held close to an uncharged metal ball on an insulating stand. The ball will Be negatively charged Be positively charged Have an excess of negative charges on the side nearest the rod Have an excess of positive charges on the side nearest the rod 35. Two bodies each carrying a charge of 2.00×10-10C are 5cm apart. Calculate the magnitude of the force between the charges. [ 1/(4πε_0 ) = 9.00×109Nm2C-2] 1.44×10-7N 7.20×10-9N 7.20×10-11N 1.44×10-11N 36. If the charge on an object is measured as 4.0×10-18C, how many excess electrons does the object possess, given that the charge of an electron is 1.6×10-19C? 18 19 25 37 37. Which of the following is a unit of the time rate of flow of electric charges? Coulomb Ampere Volt Watt 38. A wire, 1.0 m long and with cross-sectional area 2.0×10-7m2 has a resistance of 0.1Ω. Calculate the electrical conductivity of the wire. 2.0×107Ω-1m-1 5.0×107Ω-1m-1 2.0×108Ω-1m-1 5.0×108Ω-1m-1 39. Three capacitors each of capacitance 1.5μF are connected in series. The total capacitance in the circuit is 2.0 μF 1.5 μF 0.6 μF 0.5 μF 40. A voltmeter is a device that Draws high current Has a very low resistance Has a very high resistance Is able to measure both voltage and current

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41. Which of the following actions will not increase the sensitivity of a moving coil galvanometer? Using a strong temporary magnet Increasing the area and number of turns of the coil Using a weak hair spring Using a light pointer 42. Fleming’s right hand rule is also called the Motor rule Dynamo rule Screw rule Thumb rule 43. A transformer is required to supply 12Vrms to operate a toy train set from a 240Vrms. If the number of turns in the secondary coil is 100, calculate the number of turns required in the primary coil. 5 12 2000 2400 44. The diagram above illustrates a bar magnet near a coil connected to a galvanometer. When the magnet is rapidly moved towards the coil An e.m.f. is induced in the coil The galvanometer needle deflects The magnet is attracted by the coil Which of the statements above are correct? I and II only II and III only I and III only I, II and III. 45. A direct current of 5A flows through a 0.2 H inductor. Calculate the energy stored in the inductor. 0.5 J 1.0 J 2.5 J 5.0 J 46. Both -rays and x-rays Can be produced by thermionic emission Have low frequencies Have short wavelengths Which of the statements above is/are correct? I only II only III only I and III only 47. When a radioactive substance undergoes a beta decay, its Mass number decreases by 1 Atomic number decreases by 1 Mass number increases by 1 Atomic number increases by 1 48. Nuclear fission is preferred to nuclear fusion in the generation of energy because Very high temperatures are required for fusion The raw materials for fusion are easily obtained Energy obtained from fusion is relatively smaller The by-products of fusion are very dangerous 49. Control in nuclear reactors is affected with boron rods because the rods have the ability to Absorb electrons Absorb neutrons Accelerate electrons Slow down electrons 50. A radioactive element has a decay constant of 0.077 s-1. Calculate its half-life. 13.0 s 9.0 s 5.1 s 0.5 s

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