WAEC Physics 2004 Past Questions

In his first attempt, a long jumper took off from the spring board with a speed of 8 ms\(^{-1}\) at 30° to the horizontal. He makes a second attempt with the same speed at 45° to the horizontal. Given that the expression for the horizontal range of a projectile is \(\frac{u^2 sin 2\theta}{g}\) where all the symbols have their usual meanings, show that he gains a distance of 0.8576 m in his second attempt. [g = 10ms\(^{-2}\)]

The diagram above illustrates the path ABC, in a vertical x z plane, of a bullet shot into the air at an angle above the horizontal. Copy the diagram, and, using arrows, indicate the relative magnitudes and directions of the vertical and horizontal components of the velocities of the bullet at the point A, B and C.

(a) For a water voltameter, identify the;

(i) electrolyte;

(ii) electrodes;

(iii) substances deposited on the electrodes

(b)State the ratio of the volume of the substances deposited in (a) (iii) above

A parallel beam of unpolarised light is incident on a plane glass surface at an angle of 58\(^{o}\) to the normal. If the reflected beam is completely polarised, calculate the refractive index of the glass.

State three methods of polarising an unpolarised light

(a) Define diffusion

(b) State Graham's law of diffusion

A Spiral spring of natural length 20.00cm has a scale hanging freely in its lower end. When an object ass 40 g is placed in the pan. its length becomes cm. When the object is replaced with another of 60g, the length becomes 22.05cm. Calculate the mass scale pan. [g = 10 ms\(^{-2}\)]

(a) Define Young's modulus

(b) When a force of 50 N is applied to the free end of an elastic cord, an extension of 4 cm is produced in the cord. Calculate the work done on the cord.

(a) List two properties of cathode rays

(b) Explain how the intensity and energy of cathode rays may be increased

  Give three observations in support of de Broglie's assumption that moving particles behave like waves.

(a) State two;

(i) properties of x-rays

(ii) reasons to show that x-rays are waves

(iii) uses of x-rays other than those in medicine;

(iv) hazards of x-rays.

(b) The potential difference between the cathode and target of an x-ray tube is 5.00 x 10\(^4\)V and the current in the tube is 2.00 x 10\(^{-2}\)A. Given that only one percent of the total energy supplied is emitted as x-radiation, determine the  ospheric pressure.

(i) maximum frequency of the emitted radiation

(ii) rate at which heat is removed from the target in order to keep it at steady temperature. [Planck's constant, h = 6.63 x 10\(^{-34}\) Js, electronic charge e = 1.60 x 10\(^{-19}\) C]

(a) Define gravitational field intensity

(b) In an experiment to determine the acceleration of free-fall due to gravity, g, using a simple pendulum of length I, six different values of I were used to obtain six corresponding values of period T. If a graph of I along the vertical axis is plotted against T\(^2\) on the horizontal axis;

(i) make a sketch to show the nature of the graph,

(ii) write down the equation that relates T, I and g hence obtain an expression for the slope of the graph

(iii) given that the slope of the graph is 0.25, determine the value for g [Take \(\pi\) = 3.142]

(c) A stone, thrown horizontally from the top of a vertical wall with a velocity of 15 ms\(^{-1}\), hits the horizontal ground at a point 45m from the base of the wall. Calculate the

(i) times of light of the stone

(ii) height of the wall [g = 10ms\(^{-2}\)]

Define upper fixed point and lower fixed point as used in thermometry

(b) The electrical resistances of the element in a platinum restistance thermometer at 100\(^o\)C, 0\(^o\) and room temperature are 75.000, 63.000 and 64.992 \(\Omega\) respectively. Use these data to determine the room temperature.

(c) (i) State Boyle's law

(ii) A uniform capillary tube, closed at one end contained dry air trapped by a thread of mecury 8.5 x 10\(^{-2}\)m long. When the tube was held horinzontally, the length of the air column was 5.0 x 10\(^{-2}\)m, when it was held vertically with the closed end downwards, the length was 4.5 x 10\(^{-2}\)m, Determine the value of the atmospheric pressure. [g = 10ms\(^{-2}\), density of mecury = 1.36 x 10\(^4\) kg m\(^{-3}\)]

(a) Explain;

(i) wave motion

(ii) stationary wave 

(b)(i) List four physical properties of a wave

(ii) Define amplitude and use it to distinguish between the node and antinode of a stationary wave

(iii) List the factors on which the frequency of vibration in a stretched string depends

(c) The equation, y = 5 sin (3x - 4t), where y is in millimeters, x is in meres and t is in seconds represents a wave motion . Determine the;

(i) frequency

(ii) period

(iii) speed of the wave

(a) (i) Explain electromotive force

(ii) list two sources of electromotive force other than a chemical cell

(b) A chemical cell of electromotive force, E, and internal resistance, r, is connected in series with an ammeter, a plug key a plug key and an external load of resistance R. A volumeter is connected across the cell. Draw a circuit diagram to illustrate the arrangement,

(c) for the arrangement in (b) above, with the key opened and closed, the voltmeter readings are V\(_o\) and V respectively.

(i) Explain the physical meanings of V\(_o\) and V

(ii) Find an expression for the (I) current passing through the circuit (II) maximum power dissipated in the cell and external load respectively; (III) efficiency of the cell