WAEC Physics 2018 Past Questions

Practice each question, then open it to see the full details.

Question 5

During a training session, two footballers pass a ball repeatedly between each other. The 'to and fro' motion of the ball is not simple harmonic because the

I. Acceleration of the ball is not directed towards a fixed point

II. Restoring force is not directed towards the centre

III. Acceleration of the ball is not directly proportional to the displacement from a fixed point

Which of the statements above are correct?

  • A.I and III only
  • B.I and II only
  • C.II and III only
  • D.I, II and III
Objective
Question 8

 (a) Define uniform acceleration.

(b) Forces act on a car in motion. List the

(i) horizontal forces and their directions;

(ii) vertical forces and their directions

 

(c) A car starts from rest and accelerate uniformly for 20s to attain a speed of 25 ms\(^{-1}\). It maintains this speed for 30s before decelerating uniformly to rest. The total time for the journey is 60s.

(i) Sketch a velocity-tune graph for the motion.

(ii) Use the graph to determine the (\(\alpha\)) total distance travelled by the car (\(\beta\)) deceleration of the car.

The figure here illustrates force-extension graph for a stretched spiral spring. Determine the work done on the spring.

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Theory
Question 9

(a) List two factors each that affect heat loss by:

(i) radiation;

(ii) convection.

 

(b) State two factors that determine the quantity of heat in a body.

(c) Explain the statement: The vecilic latent heat of vaporization of mercury is 2.72 x 10\(^5\) Jkg\(^{-1}\).

(d)A jug of heat capacity 250 Jkg\(^{-1}\) contains water at 28°C. An electric heater of resistance 35\(\Omega\) connected to a 220 V source is used to raise the temperature of the water until it boils at 100°C in 4 minutes. After. another 5 minutes, 300 g of water has evaporated. Assuming no heat is lost to the surroundings, calculate the:

(i) mass of water in the jug before heating;

(ii) specific latent heat of vaporization of steam. [Specific heat capacity of water = 4200 kg\(^{-1}\)K\(^{-1}\)]

Theory
Question 10

(a) Define dffraction.

(b)(i) Explain critical angle. The diagram here illustrates a ray of light passing through a rectangular transparent plastic block \(\alpha\) Determine the value of the critical angle. \(\beta\) Calculate the refractive index of the block.

 

(c) A pipe closed at one end has fundamental frequency of 200Hz. The frequency of the first overtone of the closed pipe is equal to the frequency of the first overtone of an open pipe. Calculate the:

(i) fundamental frequency of the open pipe;

(ii) length of the closed pipe;

(iii) length of the open pipe. [Speed of sound in air = 330 ms\(^{-1}\)]

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Theory
Question 11

 (a) Define:

(i) reactance;

(ii) impedance in an a.c.

The diagram here illustrates an a.c. generator. When the coil is rotated, an e.m.f is induced in the coil.

(i) Explain why an e.m.f. is induced.

(ii) State the purpose of the slip-rings.

(iii) Name and state the law used to determine the direction of the induced current.

(iv) State two ways to increase the induced e.m.f.

 

(c) A lamp is rated 12 V. 6 W. Calculate the amount of energy transformed by the lamp in 5 minutes.

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Theory
Question 12

(a) Define binding energy in an atom.

(b) List three evidence to support the claim that X-rays are electromagnetic waves.

(c) List three peaceful uses of nuclear energy.

(d) Light of wavelength 4.5 x 10\(^{-7}\) in is incident on a metal resulting in the emission of photo electrons. If the work function of the metal is 3.0 x 10\(^{-9}\) J, calculate the:

(i) frequency of the incident light;

(ii) energy of the incident light;

(iii) energy of the photoelectrons. [Speed of light = 3.0 x 10\(^8\) ms\(^{-1}\), h = 6.6 x 10\(^{-34}\) Js]

Theory