2014 Physics WAEC (WASSCE) Essay Past Questions (Paper 2)

A particle is projected horizontally at 10 ms^-1 from the top of a tower 20 m high. Calculate the horizontal distance travelled by the particle when it hits the level ground. [g = 10 ms^-2]

A tennis ball projected at an angle θ attains a range R = 78 m. If the velocity imparted to the ball by the racket is 30ms^-1, calculate θ. [g = 10 ms^-2]

An electron moves with a speed of 2.00 × 10⁷ ms^-1 in an orbit in a uniform magnetic field of 1.2 × 10^-3  Calculate the radius of the orbit.

[Mass of an electron = 9.11 × 10^-31 kg, charge on an electron = 1.61 × 10^-19 C]

A metallic bar 50 cm long has a uniform cross-sectional area of 4.0 cm². If a tensile force of 35 kN produces an extension of 0.25 mm, calculate the value of Young’s modulus.

(a) Explain how a gas can be made to conduct electricity.

(b) Name the electric charge carriers in gases.

The diagram above represents the graph of electron energyEnergy is the ability to do work. Energy exists in several forms such as heat, kinetic or mechanical energy, light, potential energy, and electrical energy. Units of Energy: The SI unit... More against the frequency of the radiation incident on a metal surface. Interpret the:

(a) slope of the graph;

(b) intercept, OC;

(c) intercept, OK.

(a) State two conditions under which photo-electrons can be emitted from the surface of a metal.

(b) List two particle characteristics of electromagnetic waves.

(a) (i) Give two examples of rotational motion

(ii) Give two examples of linear motion

(b) Describe a laboratory experiment to determine the densityDensity is the measurement of how tightly a material is packed together i.e. how closely the particles are packed in the material. The tighter the material is packed the more its... More of an irregularly shaped solid.

(c) State Newton’s second law of motion

(d) Explain the term inertia

(e) (i)

The diagram above illustrates a body of mass 5.0 kg being pulled by a horizontal force F. If the body accelerates at 2.0 ms^-2 and experiences a frictional force of 5 N, calculate the;

(i)  net force on it
(ii) magnitude of F
(iii) coefficient of kinetic friction.

[g = 10 ms^-2]

(a) Define heat capacity and state its unit.

(b) List two effects of heat on a substance.

(c) Explain how a tightly fitted glass stopper could be removed from a reagent bottle.

(d) A quantity of pepper soup of mass 800 g poured into a plastic container with a tight-fitting lid has a temperature of 30^oC. The container is then placed in a microwave oven rated 1200 W and operated for 3 minutes.

(i) Calculate the final temperature attained by the soup. (Assuming no heat losses)

(ii)  Explain why containers with tight-fitting lids are not suitable for use in microwave cooking

(iii) When the soup is brought out and allowed to cool, a dent is observed on the container. Explain

[Take specific heat capacity of the soup = 4000 Jkg^-1K^-1]

(a) State the three characteristics of sound and the factor on which each of them depends.

(b) Explain resonance as applied to sound.

(c) What role does echo play in the construction of a concert hall?

(d) The surface of an eardrum (assumed circular) has a radius 2.1 mm. It resonates with an amplitude of 0.8 × 10^-7 m as a result of impulses received from an external body vibrating at 2400 Hz. If the resulting pressure change on the eardrum is 3.6 × 10^-5 NM^-2, calculate the:

(i) period of oscillation;
(ii) velocity;
(iii) acceleration;
(iv) force.

[π = 3.14]

(a) Define electromotive force.

(b) State:

(i) the principle of operation of a potentiometer.

(ii) two advantages that a potentiometer has over a voltmeter in measuring potential difference.

(c) (i) Sketch and label a diagram of a gold-leaf electroscope.

(ii) Give one use of a gold-leaf electroscope.

(d) (i) Explain the action of a magnetic relay.

(ii) List two factors that determine the magnitude of an induced emf in a coil.

(iii) A current of 5 A passes through a straight wire in a uniform magnetic field of flux density 2.0 × 10^-3 T. Calculate the force per unit length exerted on the wire when it is inclined at 30° to the field.

(a) Write Einstein’s photoelectric equation and identify each component of the equation.

(b) For a photocell, state, one factor each that is responsible for the:

(i) emission
(ii) rate of emission;
(iii) energy of photoelectrons.

(c) (i) Two nuclear equations are given below:

\( \scriptsize ^{222}_{p}RN \to \:\: ^{218}_{84}Po \: + \: ^q_2He\)  ……………….A

\(\scriptsize  ^{214}_{83}Bi \to\:\: ^{214}_{84}Po \:+ \: ^m_nX \) ………………..B

Determine the values of:

(α) p and q in equation A;
(β) m and n in equation B and identify X.

(ii) Give a reason why it is important to dispose of radioactive waste safely.

(d) (i) A certain atom emits ultra-violet photon of wavelength 2.4 × 10 ^-7m. Calculate the energy of the photon.

E₄ _______________ -6.0 × 10^-19 J
E₃ _______________ -8.2 × 10^-19 J
E₂ _______________ -8.8 × 10^-19 J
E₁ _______________ -16.7 × 10^-19 J

(ii) The figure above illustrates the energy levels of the atom. Copy the figure in your answer booklet and indicate on it, the energy level transitions which cause the emission of the photon in 13(d)(i) above.

[h = 6.6 × 10^-34 Js; c = 3.0 × 10⁸ ms^-1]