form four

TIME: 2.30HRS

INSTRUCTION

v  Answer all questions in section A and B and only one question from section B.

v  Whenever necessary use the following constants

·         Density of water=100kg/m³ or 1g/cm³

·         Acceleration due to gravity (g)=10N/Kg or 10m/s²

·         Specific heat capacity of ice=2100J/kg⁰C

·         Specific heat capacity of water=4200J/Kg⁰C

·         Specific latent heat of fusion=336,000J/kg

·         Specific latent heat of vaporization=2,260,000J/Kg

SECTION A

1.    Write a letter of the correct answer in the answer book provided.

                      i.        In thermometry, the ice point and steam point are respectively referred to as:

a)    Minimum and maximum point

b)    Freezing and boiling points

c)    Standard and fundamental temperature

d)    Lower and upper fixed points

                    ii.        Le grand pa is capable of jumping to a height of 2.62m. determine the take-off speed of the grand Pa.

a)    26.2m/s

b)    34m/s

c)    100m/s

d)    7.17m/s

                   iii.        A set of chrismas tree light consist 20 identical lamps connected in series to 240V mains supply. What are the potential differences across each lamp?

a)    12V

b)    20V

c)    240V

d)    4800V

                   iv.        Good emitters of heat energy are also.

a)    Good transmitters of heat energy

b)    Good absorbers of heat

c)    Poor absorbers of heat

d)    Good reflectors of heat

                    v.        The irregular motion of tiny particles suspended in fluid is called:

a)    Mobility

b)    Kinetic motion

c)    Random motion

d)    Brownian motion

                   vi.        The zig-zag path traversed by electrons from a negatively charged cloud towards a positively charged one is called.

a)    Lightning

b)    Field emission

c)    Radar

d)    Thunder

                  vii.        A soft iron hollow cylinder can be used to concentrate magnetic lines of force on its body, leaving the hollow part free of magnetic influence. This phenomenon is called:

a)    Magnetic induction

b)    Magnetic stroking

c)    Magnetic shielding

d)    Magnetic reduction

                viii.        Disruption of the formation of solid crystal due to the presence of impurities between the particles of liquid is called:

a)    Freezing point

b)    Triple point effect

c)    Boiling point

d)    Ambient pressure

                   ix.        A 500cm³ pyrex beaker is 95% full of methanol at 15⁰C. At what temperature will it be 100% full with the methanol?

a)    303K

b)    15K

c)    283K

d)    203⁰C

                    x.        The inverse proportionality between the volume and pressure at constant temperature represent

a)    Charle’s law

b)    Pressure law

c)    Boyle’s law

d)    Ideal gas equation

2.    Match the responses in List B with the words in List A by writing the letter of the correct response beside the item number.

LIST A

LIST B

i.              Pressure in liquid ii.            Magdeburg hemisphere iii.           Undiminished transmission of pressure in closed vessel iv.           Measure altitude of the plane v.            Draw liquid from one vessel to another vi.           Siphon principle vii.          Pressure of fluid viii.        Low atmospheric pressure ix.           Atmospheric pressure x.            Pressure at s.t.p

A.   Manometer B.   Altimeter C.   Height meter D.   Depth E.   Pascal’s principle F.    Pressure engine G.   Barometer H.   Barograph I.      760mmHg J.    780mmHg K.   Flushing tank L.    Pressure law M.   Tumbler vessel N.   Siphon O.   Air pressure P.   High boiling point Q.   Low boiling point R.   Liquid pressure S.   Ambient pressure T.    Vapour pressure U.   Verify existence of air pressure V.   Measure atmospheric concentration of gas

SECTION B

3.    (a) Define the following terms

i.              Latent Heat

ii.            specific latent heat of steam

iii.           specific latent heat of fusion

iv.           melting point

           (b) (i)Briefly explain why you feel extremely cold when sprint is spread on your head after  shaving.

                  (ii) Why it is difficult to cook at High Mountain?

            (c) Calculate the heat energy required to convert 2kg of ice at -12^oC to stem at 130^oC.

4.     (a) (i)Define turning effect of force.

                 (ii) Differentiate between stable and neutral equilibrium.

            (b) (i) Define couple.

                 (ii) What is moment of a Force?

            (c) (i) Mention two factors which affect the stability of a body.

                 (ii) A uniform rod AB, 2m long, weighs 0.4N. If weights of 0.8N and 0.4N are suspended from A and B respectively,at what point will it balance?

     

5.    (a) What is meant by the following terms

i.              Bimetallic strip

ii.            Thermostat

iii.           Linear expansivity

           (b) Briefly explain on the following observation.

              i. A cool breeze blows from the sea on a hot summer day.

             ii. Ice blocks are wrapped in a paper when stored.

           (c) A metal rod has a length of 100cm at 200oC. At what temperature will its length be 99.4cm if the linear expansivity of the material of the rod is 0.0000/k.

6.     (a)(i) Distinguish between distance and displacement.

                (ii) Define Uniform velocity and uniform acceleration.

            (b) Sketch the diagram of a body which starts from rest and accelerate uniformly for sometimes to a constant velocity and then maintains this velocity for a certain period of time before decelerating uniformly to a stop.

            (c) A bus is moving at a speed of 20m/s for 25seconds. It accelerate to a speed of 30m/s for 5 seconds before continuing moving with this speed for another 10seconds. The bus retard to rest for another 5seconds.

               (i) Draw the velocity time graph for the motion.

              (ii) Find the total distance covered for the motion.

7.    Define the following terms

         (i) Boiling point

         (ii) Freezing

         (iii) Regelation

     (b)(i) Mention four factors affecting evaporation.

         (ii) Give three differences between boiling and evaporation.

     (c)(i) The specific latent heat of vaporization of water is 2,260000J/Kg. What does this mean?

         (ii) Some hot water was added to three times its mass of water at 10oC, and the resulting temperature was 20oC, what was the temperature of the hot water?

8.    (i) What is radioactive material?

           (ii) Differentiate between Nuclear fusion and nuclear fission.

    (b) Define the term Background Radiation?

    (c) Explain the term Half-life. The half-life of thorium-234 is 24days. Calculate the mass remaining unchanged of 0.64g of the substance after 48days.

SECTION C

9.    (a)(i) Define thermionic emission.

               (ii) How x-rays is produced?

               (iii) Mention four characteristics of cathode rays.

           (b)(i) What is doping?

               (ii) Define transistor. Mention two types of transistors.

              (iii) Differentiate between conductors, semiconductors and insulators.

          (c) With the aid of diagram, describe the construction of a cathode-ray oscilloscope. State briefly the function of each of the parts of CRO.

10. (a)(i) Arrange the following rays in order of increasing frequencies.

                     X-rays, blue light, infrared light, ultraviolet light.

               (ii) Explain any three properties of Waves.

              (iii) Give one differences between Echo and reverberation.

            (b) What is Open Pipe? The open pipes have 20cm long. Find the frequency and Period of the fifth overtone. Use velocity 330m/s.

                 (c) The frequency of the wire which having 150m is 500HZ, the wire is altered up to 100m to fit the gaiter so that the sound can be heard clearly. Find the frequency after alteration,