K.C.S.E EXAM PREDICTIONS & REVISION GUIDE

1. State one difference between an image formed by a pinhole camera and the viewed through a magnifying glass.(1mk)

2. Distinguish between longitudinal and transverse waves giving one example of each. (3mks)

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3. An electric immersion heater rated 240V, 3kW is to be connected to a 240V mains supply, using a 10A fuse. Showing your working, state whether the fuse is suitable or not for circuit. (3mks)

4. Complete the following table (2mks)

Radiation	Source	Detector	Application
Radio			Communication
	Hot body		Drying clothes

5. State one defect of a simple cell and explain how it can be minimized. (2mks)

6. A wire of resistance 27 ohms is cut into three equal lengths. If the three wires are connected in parallel, what is the effective resistance? (2mks)

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7. A ray of light makes an angle of 35⁰ with the glass surface. Calculate the total distance the ray covers through a glass of refractive index 1.45, given that the width of the glass is 6cm. (3mks)

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8. (a) The table below shows the object distance u and the corresponding image distance v of an object placed in front of a convex lens.

u cm	20	25	30	40	50	70
v cm	20	16.7	15	13.3	12.5	11.5
1 cm^-1 u
1 cm^-1 V

(i) Complete the table by giving your answer to 3 d.p. 2mks

(ii) Plot a graph of 1 (y axis) against 1 4mks

v u

(iii) From the graph, determine the focal length of the lens. 2mks

(b) State any two differences between human eye and the camera. 2mks

9. Complete the ray diagram to show the position of the image 3mks.

10. Complete the ray diagram below by showing the position of the image

State one application of the set up above 5mks

11. The figure below shows how rays from a distant and near objects are focused inside a human

eye with

a certain defect

Name the defect and state two causes of the defect 3mks

12. (a) The figure below shows a set-up consisting of a mounted lens, L₁, a screen S, a metre

rule and a candle

(i) Describe how the set-up can be used to determine the focal length, f of the lens.

(3mks)

(ii)

Explain why the set-up would not work if the lens was replaced with a diverging lens (2mks)

(b) An object placed 15cm from a convex lens forms an image twice the size of the object. Determine the focal length of the lens (3mks)

13. A body in a uniform circular motion experiences acceleration despite moving at a constant speed. Explain. (2mks)

14. (a) State what is meant by centripetal acceleration. (1mk)

The figure shows masses X, Y and Z placed at different points on a turn table. The turn table is rotated at different angular velocities.

(i) State two factors that would cause the masses to slide. (2mks)

(b) At the time that start sliding off, state the mass with the highest angular velocity,

give reason for your answer. (2mks)

(c) (i)If the centripetal for is 2N and the mass and radius of the path for mass Y are 100g and 0,03m respectively. Calculate the angular velocity of the mass when the system is in equilibrium. (3mks)

15. State the name of the instrument used to take the following readings;

(i) 10 kg (1 mark)

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(ii) 0.00245m (1 mark)

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16. A micrometer screw gauge which had an error of +0.02mm was used to measure the diameter of a spherical marble. If the actual diameter was 3.67mm, draw a micrometer screw gauge showing its reading. (2 marks)

17. Fifty drops of oil have a volume of 1.0cm³. If a drop of oil forms an oil patch of diameter 20cm, determine the size of the oil molecule. (2 marks)

18. (a) A gun when fired the firer experiences equal backward recoil, explain (1 mark)

b) A man whose mass is 80kg stands on weighing machine. When the lift ascends with an acceleration of 2.45m/m², what is the reading on the scale? (2 marks)

19.

The figure below shows a sketch graph of velocity-time graph for a body falling through a liquid. Explain the motion of the motion between.

(a) B and C (1 mark)

(b) A and B (1 mark)

20. In a faulty mercury-in-glass thermometer it was found that the mercury level stands at 2 cm mark in the tube at 0⁰C and 20cm when in steam above boiling point water at normal atmospheric pressure. Calculate the temperature when the mercury stands at 13cm mark. (2 marks)

21. A balloon with argon gas of volume 199cm³ at the earth’s surface where the temperature is 21⁰C, and the pressure 760mm of mercury. If it is allowed to ascend to a height where the temperature is 2⁰C and the pressure 100mm of mercury, calculate the volume of the balloon. (2 marks)

22. (a) The spiral springs shows in the figure below are identical. Each spring has a spring constant K = 200N/m. Each rod weighs 0.1N and each spring weigh 0.1N.

Determine the total extension caused by the 150N weight. (2 marks)

(b) Apart from length of the spring and nature of material, state one other factor affecting the spring constant. (1 mark)

23. The figure below shows a cuboid in two positions. Explain how the stability of the cuboid changes when it is changed from position ‘a’ to ‘b’. (2 marks)

(a) (b)

24. (a) How does the area of support affect the stability of a body? (1 mark)

(b) The figure below shows a uniform rod AE which is 40cm long. It has a mass of 2kg and pivoted at D. If 2N is acting at point E, and 30N force is passed through a frictionless pulley.

Find the force X acting at end A. (3 marks)

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b) An effort of 450N is used to raise a load of 2700N. Determine:

i) Mechanical advantage (M.A) (2 marks)

(ii) Efficiency of the pulley system. (2 marks)

(iii) If all the wasted energy is used to raise the lower block and the frictional force between pulleys and moving parts is 3.6N; determine the weight of the lower block. (2 marks)

(d) James applied a force of 400N in pushing a stationery wall. If he took one hour to push the wall, calculate the power developed. (1 mark)

26. (a) The figure below shows dots which were made by a ticker timer – tape attached to a trolley. Thetrolley was moving in thedirection shown.

If the frequency used was 60Hz, distance AB = 12cm and BC = 7.2cm, determine

(i) The velocities between AB and BC (2 marks)

(ii) The acceleration of the trolley. (2 marks)

(b) An object is projected horizontally with a velocity of 40m/s at the top of a cliff 100m from the ground. (Take g = 10m/s²)

(i) Calculate the time taken for the object to hit the ground (3 marks)

(ii) What is the range of the object from the foot of the cliff (2 marks)

(b) State two assumptions that were made when deriving the equation of continuity?(2marks)

27. (a) A ship made of steel is able to float while a steel rod sinks explain. (1 mark)

(b) A block of length 50cm, cross-sectional area of 5cm² and density 1.4g/cm³ is completely immersed in a liquid of density

1.08g/cm3 find

(i) the mass of the block (2 marks)

(ii) the weight of the block in the liquid. (2 marks)

(iii) the apparent loss in weight of the block if three quarter of it is immersed in the liquid. (2 marks)

28. (a) Define specific latent heat of fusion (1 mark)

(b) Given the following. A filter funnel, a thermometer, a stop watch, ice at 0⁰C, animmersion heater rated P watts, a beaker, a stand, boss and clamp and weighing machine. Describe an experiment to determine the specific latent heat of fusion of ice. Clearly state the measurements to be made. (4 marks)

(c) 200g of ice at 0⁰C is added to 400g water in a well lagged calorimeter of mass 40g. The initial temperature of the water was 40⁰C. If the final temperature of the mixture is X⁰C, (Specific latent of fusion of ice L = 3.36 x 10⁵JKg^-1, specific heat capacity of water, c = 4200Jkg^-1K^-1,specific heat capacity of copper = 400Jkg^-1K^-1)

(i) Derive an expression for the amount of heat gained by ice to melt it and raise its temperature to X⁰C (2 marks)

(ii) Derive an expression for the amount of heat lost by the calorimeter and its content when their temperature falls to X⁰C. (2 marks)

(iii) Determine the value of X. (3 marks)

29. (a) The moon goes round the earth at constant speed. Explain why it is true to say that the moon is accelerating. (1 mark)

(b) A string of negligible mass has a bucket tied at the end. The string is 60cm long and the bucket has a mass of 45g. The bucket is swung horizontally making 6 revolutions per second. Calculate:

(i) The angular velocity. (1 mark)

(ii) The centripetal acceleration. (2 marks)

(iii) The tension on the string. (2 marks)

(iv) The linear velocity. (1 mark)

(c) Figure 6 shows of mass m = 200g attached to the centre of a rotating table with a string. The radius of the spring was varied and different values of angular velocity recorded. The mass of the body remained constant throughout the experiment.