PRESIDENT’S OFFICE

REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT

COMPETENCY BASED EXAMS

SECONDARY EXAMINATION SERIES

FORM THREE TERMINAL EXAMINATION

031            PHYSICS 

TIME : 3HRS                                                                          AUG,2023

INSTRUCTIONS 

1.                This paper consists of section A, B, and C with a total of  eleven (11) questions
2.                Answer all questions in section A and B and any two (2) questions from section C
3.                Show clearly  your work
4.                Section A carries fifteen (15)marks, section B sixty (60) marks and section C carries twenty five (25) marks
5.                All writing should be in blue or black pen except for diagrams that must be drawn in pencil.
6.                Non-programmable calculator may be used
7.                Cellular phones and any unauthorized materials are not allowed in the examination room.
8.                Write your examination  number on each page of your answer sheet(s)
9.                 Where necessary, use the following constants

-                      Acceleration due to gravity(g) = 10m/s²

-                      Density of water = 1g/cm³ or 1000kg/m³

SECTION A (15 MARKS)

Answer all questions in this section

1.  
2. For items (i) –(x) Choose the most correct answer from the alternatives given

1.      The same body is immersed in liquid A and then, in liquid B. The to which the body sinks in liquid B is less than in liquid A. What conclusion can be derived from such observation?

1. The density of liquid A is more than the density of liquid B.
2. The density of liquid B is more than the density of liquid B.
3. The density of solid is less than that of the liquid in both cases
4. The density of liquid A is the same as that of liquid B

2.    A person measures the length, width, height and mass of a rectangular metal block. Which of these measurements must be used in order to calculate the density of the metal?

1. Mass only
2. Height and mass only
3. Length, width and height only
4. Length, width, height and mass
5. Width, height and mass

3.  What is the force acting on a book that is dropping in to the floor?

1. Air resistance only
2. Gravity and air resistance
3. Gravity only
4. Friction only
5. Air resistance and friction.

4.                                                                               The refractive index of a glass block cannot be evaluated from the following ratios;

1.                                                                   Sin i to sin r
2.                                                                   Velocity of light in air to the velocity of light in glass
3.                                                                   Frequency of light in air to the frequency of light in glass
4.                                                                  Real depth to apparent depth

5.    Water in bath varies in depth from 20.0 cm at the shallow to 30.0 cm at the end of the plug as shown in the figure below

What is the pressure of water acting on the plug?

1. 0.98 kPa
2. 2.0 kPa
3. 2.9 kPa
4. 290 kPa
5. 2.1 kPa

6.  If you are caught outside during a severe thunderstorm, you should:

1. Take shelter under the nearest tree
2. Stand under power lines
3. Move to higher ground
4. Hide in a ditch
5. Run to the nearest car

7.       Action and reaction forces never cancel each other because;

1. They are not equal in magnitude
2. They are in the same direction
3. They act on different direction
4. They act on different objects
5. None of the above

8.     A force of 3.5 N acts horizontally on an object. Another force of 5 N acts on the same object at an angle of 45° to the horizontal. Which of the following is the resultant force?

1. 8.2 N
2. 8.5 N
3. 6.1 N
4. 7.9 N
5. 7.7 N

9.   Mawazo has worn a yellow t-shirt. He spills cyan coloured ink on it. What colour will the stain appear?

1. Green
2. Blue
3. Yellow
4. Cyan
5. Red

10.                                                                                 A concave mirror is often used as a shaving mirror, this is possible if the face is placed ;

1.                                                                   Beyond center of curvature
2.                                                                   Near the mirror
3.                                                                   Between the principle focus and the pole
4.                                                                  At the center of curvature

2. Match the colours from List B which absorbed by the colour in List A by writing the letter of the correct response beside the corresponding item number in the answer booklet provided. (06 Marks)

SECTION B (54 Marks)

Answer all questions in this section.

3. a) A nail is being pulled using a string from a wall .The string forms an  

    angle of 30⁰ with the nail if the force being used is 10N  part of the force  

    will tend to bend the nail while other part will   try to pull it out 

1.                     what magnitude of the force tends to bend the nail (03 marks)
2.                   what magnitude of the force tends to pull the nail out ( 03marks)

b)   The velocity of car B relative to car A is 8m/s when the two cars are   

                 moving in the same  direction and 28m/s when the  two cars are moving   

                 in opposite directions Determine  the velocity of each car (03 marks)

4. (a) An aluminium block of mass 2.1kg rests on steel platform  A horizontal 

    force of 15N is applied  to the block 

1.                   given the limiting friction between the surfaces is 0.61 will the block move (03marks)
2.                 if it moves, What will be its acceleration  coefficient of  kinetic friction is 0.47 (03 marks)

         (b)  Explain why most vehicles have their engines directly over the drive   

                 wheels (03 marks)

5. (a) Briefly explain the rules used to locate images in curved mirrors.

                                                                                                   (04 marks)

(b) Draw rays diagram for concave mirror showing nature of the images   

     when the objects is at the following   positions 

1.                   object at centre of curvature. (02.5marks)
2.                 object beyond the centre of curvature. ( 02.5 mark)

6. (a) Briefly explain why convex mirror is used as driving mirrors (03 marks)

(b) A concave mirror with radius of curvature 30cm produces an inverted   

     image 4 times the size  of an object  placed on its principal axis   

     Determine the position of the object and that of images   (06 marks)

7. (a) State the factors that affect the stability of the body (02 marks)

(b) A uniform wooden plank with a mass of 75kg and length of 5m is placed  

    on top of a brick wall so that 1.5m of the plank extends beyond the walls  

    edge . how far beyond the edge of the wall can 100kg woman walk before   

    the plank begins to rotate. Let the planks axis of rotation be at the walls   

    edge (07 marks)

8. (a) A block and tackle  system  consisting of a 5 pulleys used to raise a load 

    of 400N trough height of 10m if the work done against friction is 100J  

   .Calculate 

1.                    the  work done by the effort (02.5marks)
2.                   the efficiency of the system (02.5 marks)

           (b) Figure below shows a cross section of bicycle wheel. The wheel has a  

                 radius of 35cm while rear sprocket has radius of 3.5cm. Assume that the  

                   wheel drivers both sprocket and axle

                  if the axle has a radius of 1cm , determine 

1.                     the velocity ratio of the sprocket and axle  (02marks)
2.                   the velocity ratio of the wheel and axle (02 marks)

SECTION C (30 Marks)

Answer two (2) questions from this section.

9. (a) A trolley of mass 20kg loaded with a bag of maize of mass 100kg rests  

    on smooth horizontal track .IF two opposing forces of magnitude 55N and   

    90N are applied to the trolley as shown

1.                     find acceleration of the trolley (04 marks)
2.                   the distance travelled by trolley in 4 seconds (04 marks)

              (b) Show that the third equation of motion in straight line is given by 

                                                             (07 marks)

10. (a) (i) Explain how geothermal energy is harvested (05 marks)

     (ii) Give two advantages and two disadvantages of geothermal energy    

           (04 marks)

            (b) (i) Give three advantages and three disadvantages of wind energy. 

                                                                                   (06 marks)

11.  (a) A box is being pulled on the floor using a string, the string makes an 

      angle of 30⁰ with the box.

   if the force being applied at the string is 200N find 

1.                   the force which tends to pull the box forward  (03 marks)
2.                 the force which tends  to lift the box  (03 marks)

             b)  Two cables stays are used to support a pole as shown below 

if the tension in the cable AB and AD is 500N and 160N respectively. Determine magnitude and direction of the resultant of the forces exerted by the stays at A using parallelogram law. (09 marks)

PRESIDENT OFFICE REGIONAL ADMNISTRATION

AND LOCAL GOVERNMENT

SECONDARY EXAMINATION SERIES 

COMPETENCE BASED ASSEMENT

PHYSICS FORM THREE

TERMINAL EXAMS MAY – 2023 

TIME: 3:00HRS

Instructions

1. This paper consists of section A, B and C
2. Answer all questions in section A and B and only one question from section c
3. Whenever necessary the following constants may be applied

1. Acceleration due to gravity “g” = 10M/S²
2. Specific latent heat of vaporization of water (LV)=2.3 x 10⁶ J/Kg
3. Specific latent heat of fusion of water (L_f)=3.35 x 10⁵ J/kg
4. Density of water = 1000kg/m³
5. Specific heat capacity of water (Cw) = 4200J/Kg°C

1. For each of the items (i) – (x) choose the correct answer from among the given alternative and write its letter beside the item number.

1. Diffusion occurs more quickly in a gas than in liquid because;

1. The liquid contains a layer on its surface
2. The gas contains semi-permeable membrane
3. The gas molecules is small in size compared to the liquid molecules
4. The adhesion is large than cohesion in gas compared to that in liquid.
5. The speed of molecules in gas is greater than in liquid

2. In a loading a lorry a man lifts boxes each of weight 100N through a height of 1.5m, if he lifts 4boxes per minute, the average power the man is working is;

1. 100
2. 10
3. 600
4. 37.5
5. 2250

3. In a process of charging by induction in static electricity

1. A conductor is rubbed with an insulator
2. Charge is produced by friction
3. Negative and positive charges are separated
4. A positive charge induces a positive charge
5. Electrons are sprayed into an object

4. Which of these resources of energy is non-renewable?

1. Wave energy
2. Bio fuels
3. Radiant energy
4. Fossil fuel
5. Geothermal energy

5. The temperature of a certain liquid is measured to be 273k. What will be its temperature in degree centigrade?

1. 2370C
2. 100°C
3. 57°C
4. 0°C
5. 37°C

6. The difference between a scalar and vector quantity is that;

1. Scalar has a magnitude only
2. A vector has magnitude and direction while scalar has magnitude only
3. A scalar has both magnitude and direction while vector has magnitude only
4. A scalar has both magnitude and direction
5. All of the above mentioned are the correct answers

7. Mercury forms spherical drops when split on a glass surface, this is because.........

1. It has high adhesive force
2. It has high cohesive force
3. It has high surface tension
4. It has high relative density
5. It has high viscosity

8. Repulsion is the force that push object against each other. This results when

1. Magnet of the same poles
2. Magnet of opposite poles
3. Dipole of magnetic
4. Magnet domain

9. The movement of liquid from low to high concentration through a semi permeable is called

1. Diffusion
2. Fusion
3. Osmosis
4. Osmotic pressure
5. Brownian motion

10. An instrument used to measure length to the accuracy of 0.1mm is..........

1. Tape measure
2. Micrometer screw gauge
3. Meter rule
4. Venire calipers
5. Classroom ruler

2. Match the items in List A with responses to List B by writing the letter of the correct response beside the item number in the answer sheet provided.

SECTION B

Answer all questions from this section

3. (a)A body dipped in a liquid experiences an upthrust. Explain three factors on which the upthrust depends

(b)Two identical free running trolleys are on a smooth horizontal runway. One trolley is at and the other approaches it at constant speed of 20m/s

1. Use the principle of conservation of momentum find the common speed of two trolleys after the collision
2. Why the kinetic energies before and after the collision are different?

4. (a)A uniform half metre rule is balanced at 15cm mark when a load of 0.4N is hanging at the zero mark. Draw a sketched diagram indicating the arrow of weight of the rule acting through the centre of gravity hence determine the weight of the half metre rule.

(b)A screw jack a screw pitch of 5mm and the effort arm of 16cm

1. State two forms of energy in which the energy supplied to the screw jack is finally converted to
2. Determine the percentage efficiency of this screw jack, if it needs an effort of 30N to lift a load of 750N
3. Why mechanical advantage is unitless?

1. Define pressure
2. Why at the bottom of the dam the wall constructed thicker?
3. Why water flows more easily than other liquids like honey
4. A person at high altitude suffer nose bleeding, explain why
5. From the concept of pressure we explaining that pressure may be affected by several factors, mention at least three factors affecting liquid pressure.

6. (a)(i)State ways to improve the efficiency of machines

(ii)The figure below shows the system of pulley used to raise a load by applying effort of 500N

State the velocity ratio and purpose of pulley 2.

(b)Given that the machine has an efficiency of 80%. Calculate the maximum load that can raised.

1. The specific heat capacity of a certain substance is 800J/Kg°C. What does this statement mean?
2. Why do we feel colder when wet?
3. An insulated cup holds 0.3kg of water at 0°C. 0.2kg of boiling water at standard pressure is poured in the cup. What will be the final temperature?

8. (a)Give reasons for the following;

1. A gap is left between two successive rails
2. A glass tumbler breaks when hot liquid is poured into it.

(b)Mention three applications of thermal expansion of a solid.

SECTION C

Answer two (2) questions from this section

9. (a)(i)Why in case of liquids we distinguish between the coefficients of apparent and real expansion whereas in case of gases not, Explain.

(ii)The absolute expansivity of mercury is 0.0018°C – 1. Find the apparent volume expansivity of mercury in glass given that linear expansivity of glass is 0.00009°C-1.

(b)(i)Define linear expansivity of a substance.

(ii)A copper rod has a length of 40cm on a day when the temperature is 22.3°C. What will its length be on a day when the temperature is 30°C. (liners expansivity of copper is 0.000017°C).

10.                      (a)Define the following terms;

1. Heat capacity
2. Specific heat capacity
3. Shortly explain the methods of heat transfer

(b)(i)Give three points that the amount of heat supplied or taken away from a substance depends on;

(ii)A 100g piece of metal at 100°C is placed into 120g of water at 16°C in the vessel of negligible heat capacity. If the final temperature is 28°C. Calculate the specific heat capacity of the metal. (Specific heat capacity of water is 4200J/Kg°)

11.                      (a)The diagram below show a bimetallic thermostat used to regulate a cooler and heater in a class room. It consist a brass of linear expansivity 18.9 x 10-4K-1 and iron of linear expansivity 10.2 x 10-4K-1. To keep the temperature in the room constant, which of the two devices A or B should be the heater? Explain your answer.

(b)Three beakers are of identical size and shape; one beaker is painted matt black, one is dull white and one is gloss white. The beakers are filled with boiling water

1. In which beaker will the water cool most quickly? Give a reason
2. State a process in addition to conduction, convection and radiation, by which heat energy will be lost from the beaker.