PHYSICS PAPER 1 - 2019 KCSE KASSU JOINT MOCK EXAMS (QUESTIONS AND ANSWERS)

Instructions to candidates

• Answer all questions in this question paper.
• Answers to all questions must be written in the spaces provided in this booklet.
• This paper consists of Two Sections A and B in the spaces provided.
• All working MUST be clearly shown.
• Electronic calculators and mathematical tables may be used.

SECTION A: (25 MARKS)

1. The figure below shows a section of a burette after 51g of liquid has been run out of it.
   
   If the burette was filled to the zero mark at the start, calculate the density of the liquid in SI units   (3 marks)

2. A hose pipe of internal cross-section area of 12cm² is connected to a sprinkler with identical holes each of area 0.008cm The water in the pipe flows at a speed of 5cm/s. If water leaves the sprinkler with a velocity of 3m/s, calculate the number of holes in the sprinkler.                    (3 marks)

3. State the reason why you would be able to jump higher on moon’s surface than you can on the earth’s surface (1 mark)

4. State one way of making the surface tension of a liquid stronger. (1 mark)

5. Seen in a microscope, pollen grains placed on the surface of water, move about irregularly. Explain this observation (2 marks)

6. The figure below shows a uniform beam held at equilibrium as shown
   
   Calculate the weight of the beam      (3 marks)

7. The figure (a) below shows a velocity – time graph
   
   Sketch in figure (b) the speed – time graph of the same motion    (1 mark)

8. Explain why a drop of methylated spirit placed on the back of the hand feels colder than a drop of water although at the same temperature (2 marks)

9. State the law of floatation (1 mark)

10. A spring of elastic constant K has its length increased from 4.00m when unloaded to 4.25m when loaded with a mass of 7500g. Assuming that the elastic limit is not exceeded, determine the value of K. (2 marks)
11. Figure (a) and (b) below shows two identical trolley X and Y carrying loads A and B of the same size respectively. Given that the density of A is lower than that of B.
    
    
    1. State which trolley is less stable (1 mark)
    2. Explain the answer in (i) above (2 marks)

12. The atmospheric pressure of place X is 9m of water. A farmer residing in the area constructs a fish pond that is 12m deep. Calculate the pressure experienced by a fish at the bottom of the pond. (g = 10N/Kg and density of water = 1000Kg/m³) (3 mks)

SECTION B: (55 MARKS)

13.  
    1. State Newton’s second Law of motion (1 mark)
    2. The initial velocity o f a body of mass 50Kg is 10m/s. A constant resultant force of 15N is then applied.                                                                                    
       1. Calculate the initial Kinetic energy of the body.       (1 mark)
       2. Calculate the time it takes to double the kinetic energy of the body after the force is applied    (4 marks)
    3. Describe the motion of a small steel bearing that is dropped at the surface of glycerine in a tall measuring cylinder.       (2 marks)
14.  
    1. What is meant by absolute Zero temperature        (1 mark)
    2. State Charles’ Law        (1 mark)
    3. When the temperature of a gas in a closed container is raised, the pressure of the gas increases. Explain how the molecules of the gas cause the increase in pressure  (2 marks)
    4. 200cm³ of dry gas at 0 C and 760mmHg is heated to 100 . Calculate the new pressure assuming the volume of the container carrying the gas does not change (3 marks)
    5. State two quantities that must be kept constant in order to verify Boyle’s Law. (2 marks)
15.  
    1. State two factors that affect melting point of a substance                            (2 marks)
    2. 32g of ice at 0 C was added to 200g of water at 25 C in a beaker of negligible heat capacity. When all ice had melted the temperature of water was found to be 10 C. (Take specific heat capacity of water as 4200J/KgK)
       1. Calculate the heat lost by the water.         (2 marks)
       2. Calculate the specific latent heat of fusion of ice       (3 marks)
    3. Define the term specific latent heat of vapourisation        (1 mark)
16.  
    1. A block of steel sinks in water while a ship which is mainly made of steel floats. Explain.  (2 marks)
    2. A solid weighs 50N in air and 45N when completely immersed in water of density 1g/cm³. Determine the density of the solid     (3 marks)
    3. A cubic block, of side 30cm and density 800Kg/m³ , is attached to the base of a tank containing water of density 1000Kg/m³ by means of an inextensible cable of negligible mass as shown (Take g = 10m/s²)
       
       Calculate:
       1. The weight of the block (3 marks)
       2. The upthrust acting on the block (2 marks)
       3. The tension in the cable (2 marks)

17.  
    1. Define the term Angular velocity (1 marks)
    2. The diagram in the figure below shows a mass 2Kg, which is rotated in a vertical circle. The speed of the mass is gradually increased until the string breaks. The string breaks when the mass is at its lowest position A and at a speed of 40m/s. Point A is 8m above the ground.
       
       
       1. Calculate the angular velocity of the body just before the string breaks.(2 marks)
       2. Calculate the maximum tension on the string at point A just before it breaks.(3 marks)
    3. Show on the diagram, the path of the mass from point A until it strikes the ground when the string breaks           (1 mark)
       Calculate:
       1. The time the mass takes to reach the ground after breaking off (2 marks)
       2. The horizontal distance the mass travels before it strikes the ground.(2 marks)

18.  
    1. Define the term mechanical advantage of a machine (1 mark)
    2. A cyclist initially at rest moved down a hill without pedaling. He applied brakes and eventually stopped. State the energy changes as the cyclist moved down the hill      (2 marks)
    3. A wheel and axle is used to raise a load of 200N. Given that the radius of the large wheel is 10cm, that of the small wheel is 5cm and the efficiency of the machine is 80%. Determine the effort required to raise the load.  (4 marks)