PHYSICS PAPER 1 - 2019 MOKASA II MOCK EXAMINATION

Instructions to candidates

• This paper consists of two sections A and B.
• Answer all the questions in the two sections in the spaces provided after each question
• All working must be clearly shown.
• Electronic calculators and Mathematical tables may be used.
• All numerical answers should be expressed in the decimal notations.

SECTION A (25 MARKS)

Answer all the questions in this section in the spaces provided.

1. Figure 1. shows a micrometer screw gauge being used to measure the diameter of a ball bearing.
   
   If the instrument has a negative zero error of 0.01mm, record the actual diameter of the ball bearing.                                                                                                        (1mark)

2. Figure 2. shows drops of mercury and water on a glass surface,
   
   Explain the difference in the shapes of the drops.       (2 marks)

3. State why diffusion is faster in gases than in liquids. (1mark)

4. When a Bunsen burner is lit above a wire gauze, it is observed that the flame initially burns above the gauze shown in figure 3 (i). After sometime, the flame burns below as well as above the gauze as shown in figure 3(ii).
    
   Explain the observation.     (2marks)

5. In an experiment to demonstrate Brownian motion, smoke was placed in a smoke cell and observed using a microscope. The smoke particles were seen moving randomly in the cell. Explain the observation.     (1mark)

6. A paper vane in a horizontal axis was placed above a Bunsen burner as shown in figure 4. When the burner was lit, the paper vane begun to rotate. Explain the observation.   (2marks)
   

7. An electric kettle with shiny outer surface is more efficient than one with a dull outer surface, give a reason for this. (1mark)

8. What is the reason why trailers carrying heavy loads have many wheels. (1mark)

9. Two flasks A and B were placed on a horizontal surface as shown in figure 5.
   
   State and explain which flask is more stable.                                                 (2marks)

10. Figure. 6 below shows a metre rule balancing when a mass of 200g is hung at one end. Determine the tension, T in the string.      (3marks)
    

11. State Newton’s second law of motion. (1mark)

12. A pipe of diameter 12mm is connected to another of diameter18mm. if water flows in the wider pipe at the speed of 2m/s, determine the speed of water in the narrow pipe. (3marks)

13. On the axes provided in the figure 7, sketch the graph showing variation in pressure with volume of a fixed mass of gas that obeys Boyle’s law. (1mark)
     

14. An oil drop has a volume of 0.01mm³. When it is placed on the surface of water, it spreads out to form a circular patch of area 500cm².
    1. Calculate the size of the molecule of the oil.         (3marks)
    2. State one assumption made in (i) above.                                                   (1mark)

SECTION B (55 marks)

15.  
    1. Define angular velocity (1 mark)
       
    2. The figure below shows an object of mass 0.2kg whirled in a vertical circle of radius 0.3m at uniform speed of 4m/s
    3. Determine the tension of the string at:
       1. Position A                                                                                                   (2 marks)
       2. Position B                                                                                                  (2 marks)
       3. Suggest the point where the string is likely to snap.                                (1 mark)
          
    4. The figure below shows the motion of a trolley on a ticker tape timer whose frequency is 100HZ
       Determine:
       1. Initial velocity at points AB.                                                                                  (2 marks)
       2. Velocity at points CD                                                                                           (2 marks)
       3. Acceleration of the trolley during the motion.                                                     (2 marks)

16.  
    1. Give the reason why a density bottle is more accurate than a measuring cylinder when used to measure volume of liquids. (1 mark)
    2. State two precautions taken when using a density bottle.   (2 marks)
    3. A form one student wanted to determine the density of copper. She wrote the following procedure: Study it and answer the questions that follow.
       1. Measure the mass x₁ (g) of a clean dry empty density bottle
       2. Fill the bottle partly with copper turnings and measure the mass x₂(g)
       3. Fill the bottle with water up to the neck and measure its mass x₃(g)
       4. Empty the bottle and rinse it.
       5. Fill it with water and replace the stopper. Measure the mass x₄(g) of the bottle filled with water.
          Write an expression for:
          1. Volume of the bottle      (2 marks)
          2. Mass of copper turnings       (1 mark)
          3. Volume of copper turnings.     (2 marks)
          4. Density of copper.         (2 marks)

17.  
    1. State the law of floatation (1 mark)
    2. A metal block weighs 0.8N is suspended by a string in water. If the block is completely immersed in water the tension in the string is 0.5N. Find
       1. The upthrust on the block      (1 mark)
       2.  The density of the block.   (3 marks)
       3. The figure below shows a cork of mass 25g floating in water.
          
          Determine the minimum volume of copper that must be attached so that the two will just submerge.( Relative density of copper = 9.0, Relative density of cork= 0.25)(3marks)
    3. Explain how a submarine can be made to.
       1. Float on water   (1 mark)
18.  
    1. You are provided with the following apparatus: A filter funnel, a thermometer, a stop watch, ice at 0°C, an immersion heater rated P watts, a beaker, a stand, boss and clamp and a weighing machine. Describe an experiment to determine the specific latent heat of fusion of ice. Clearly state the measurements to be made.         (3marks)
    2. 200 g of ice at 0°C is added to 400g water in a well lagged calorimeter of mass 40g. The initial temperature of the water was 40°C. If the final temperature of the mixture is X°C,(Specific latent of fusion of ice L = 3.36 x 10⁵ Jkg^-1, specific heat capacity of water, c = 4200Jkg^-1K^-1, specific heat capacity of copper = 400 Jkg^-1K^-1.)
       1. Derive an expression for the amount of heat gained by ice to melt it and raise its temperature to X°C      (2marks)
       2. Derive an expression for the amount of heat lost by the calorimeter and its content when their temperature falls to X°C.                                (2marks)
       3. Determine the value of X.        (3marks)
    3.  A hydrogen balloon of volume 1.2 m³ is released at the ground level where the pressure is680 mmHg and a temperature of 20 °C. Determine the volume of the balloon at a height of2500m above the ground where the pressure drops to 500 mmHg and the temperature is 4°C.                                                            (4marks)

19. A balloon seller has a cylinder of helium gas which he uses to blow up his balloons. The volume of the cylinder is 0.10m³. It contains helium gas at a pressure of 1.0 x 10⁷Nm^-2. The balloon seller fills each balloon to a volume of 1.0 x 10^-2m³ and a pressure of 2.0 x 10⁵N/m²
    1. Explain in terms of particles how the helium in the cylinder produces a pressure      (1mark)
    2. Calculate the total volume that the helium gases occupy at a pressure of 1.2 x 10⁵ N/m². Assume the temperature of the helium does not change               (3marks)
    3. Calculate the number of balloons of volume 1.0 x 10^-2m³ that the balloon seller can fill using the gas                       (2marks)
    4. The graph below shows how the pressure of a gas trapped inside a sealed container  changes with temperature. The pressure is caused by the gas particles continually hitting the sides of the container.
       
       1. Write down the name of the temperature at which the gas particles stop hitting the sides of the container      (1mark)
       2. What is the momentum of the gas particles at this temperature? Give reason for the Answer          (2marks)
       3. Give the value of the temperature in Kelvin                           (1 mark) 

MARKING SCHEME