ENGINEERING SCINCE QUESTION BATCH 01 2025

 

ENGINEERING SCIENCE

1.(a) (i)state the law of conservation of energy

        (ii) mention any three form of energy

   (b)an electric heater of 2 kilo ohm resistance uses current of 15A to heat water from 20⁰C to 90⁰C in      15sec take the specific heat capacity of water to be 4.2kj/kg.

      Calculate the;

                        (i)electric power of heater

                        (ii)the mass of water

2. (a)(i) mention two type of frictions

         (ii) mention two disadvantage of friction

        (iii) briefly explain how you can reduce friction

  (b)  a body having a mass of 40kg rest on a table horizontally and it is found that horizontal required moving the body is 90N . calculate coefficient of friction (use g=10m/s²)

3. (a) from the following quantity identify which is scalar or vector quantity

          (i)speed and velocity

          (ii)mass and weght

     (b)a body of mass 200kg increases it speed from 54km/h to 108km/h in 30sec. calculate

          (i) Distance travelled during acceleration

         (ii) Force exerted

4. (a) mention any two uses of knowing density of materials

     (b) Define the term density and relative density 

     (c) a solid material of mass 0.0048kg is lowered into measuring cylinder of water level of 36cm³. If water level rises to 53.9cm³. determine

          (i)volume of solid

          (ii)density of material in both g/cm³ and kg/m³

5. (a) there are three classes of levelers. By aid of diagram

        (i)show each one clearly indicating the position of the load, effort and pivot

         (ii) mention one typical example of each of three classes of levers

6. (a) (i) define centripetal acceleration

         (ii)an object of mass 6kg is whirled round a vertical circle of radius 2m with a speed of 8m/s. calculate minimum tension of string connecting an object to centre of circle

  (b) a stirrer in food mixer rotate so that the end of it moving round once is 0.07s. if length of stirrer arm is 9cm, calculate

          (i)the linear velocity at the end of arm

          (ii)the linear velocity half way along the arm

          (III) the number of revolutions per second (frequency)

7. (a)define

        (i)limiting friction                                           (ii) dynamic friction

   (b)differentiate between mass and weight

   (c)mention four factors affecting friction

   (d)a loaded trailer weighing 25tones in being towed at constant speed across a level roadway whose coefficient of dynamic friction is 0.25. determine friction force in the trailer (use g=10m/s²

8. (a) define the following terminology as applied to strength of material

        (i) young modulus                             (ii)strain

    (b) a steel bar with cross section area of 2cm³ is heated raising it temperature by 120⁰c and prevented from expanding

         Calculate the resulting force in the bar. Young modulus for steel =2.1x10¹¹ Pa, linear expansivity=0.000012k^-1

9. (a) distinguish between specific heat capacity and heat capacity

    (b) a copper saucepan of mass 250g is filled with 850g of water at 18⁰c . a 500W heater is then placed in water  and switched on for two minutes. Find final temperature after this time

           Use specific heat capacity of copper=385J/KgK^-1 and water=4200J/KgK^-1

10. (a) (i)differentiate between kinetic energy and potential energy

            (ii)give two factors that work depend

     (b)a lorry of mass 6000kg travel along levei road a 30ms^-1. The brakes are then applied and lorry stop in 70m. calculate  (i) the kinetic energy of lorry before braking

                                 (ii) the braking force