PHYSICS PAPER 1 - 2019 KCSE Prediction Questions Set 2

INSTRUCTIONS

1. Answer all questions in section A and B 
2. All working for numerical questions must be clearly shown;
3. Non programmable silent electronic calculators may be used
4. The paper is out of 80 marks;

CONSTANTS
You may use the following constants where necessary

1. Refractive index of water = ⁴/₃
2. Earth’s gravitational strength = 10Nkg^-1;
3. Density of water = 1,000kgm^-3;
4. Atmospheric pressure = 76cmHg
5. Speed of Sound is 330ms^-1
6. Refractive index of glass = ³/₂
7. Density of mercury = 13,600kgm^-3

SECTION A (25 Marks)

Answer all the questions in this section in the spaces provided

1. Figure 1(a) below shows a micrometer screw gauge when closed and Figure 1(b) shows the same micrometer screw gauge measuring the thickness of a wire. 
   Determine the thickness of the wire    (2mks)
   
   Figure 1a and Figure 1b
2. A form two student was provided with two springs to make a spring balances, she sets up two designs as shown below in Figure 2(a) and Figure 2(b)
   With reason(s) state which two designs you would use to measure the weight of a heavy load?   (2mks)
   
   Figure 2a and Figure 2b
3. A rectangular container measures 2 cm by 4cm by 5cm. What is the weight of the mercury that will fill the container to the brim?  (3mks)
4. Figure 3 below shows a U-tube connected to a gas supply. Determine the pressure of the gas in cmHg
   
   Figure 3
5. Three iron sheets meant for construction in hot regions have oval- shaped holes. Bolts are used to fix them on the roof through the oval holes. Explain the importance of the shape of the holes. (1mk)
6. Figure 4 below shows paper kite 
   
   Figure 4
   Fast moving air is blown horizontally under the kite as shown in the diagram. State and explain the observation made.     (2mks)
7. Figure 5 below shows a light rod balanced by the forces shown. M is a magnet of weight 5N and P is a permanent magnet fixed on the bench. (2mks)
   
   Figure 5
   Find the attraction force between M and P.
8. A heating coil rated 1000w takes 20 minutes to heat 10kg of a liquid from 25^oC to 65^oC Determine the specific heat capacity of the liquid. (Assume no heat is lost to the surroundings).
9. Figure 6 below shows 3 identical masses m₁, m₂ and m₃ placed on a smooth rotating
   
   Figure 6
   State the factors that determine whether a particular mass slides off table or not.                (1mk)
10. Ice is in a beaker which is placed in a table as shown in Figure 7 below.
    
    Figure 7
    The ice is heated until it melts. Explain what happens to the stability of the beaker     (2mks)
11. What is the velocity ratio of the pulley system shown in the figure below? (1mk)
    
12. Figure 8 below shows how the displacement of a point varies with time as a wave passes it.
    
    Figure 8
    On the same diagram draw a wave which passes the point with half the amplitude and twice the frequency.  (2mks)
13. A part from pressure state another factor that affects the melting point of a substance. (1mk)

SECTION B (55 MARKS)
Answer all questions in this section

14.  
    1. A piece of wood weighs 5.0N in air and 0.45N when immersed in water
       Determine;
       1. its relative density           (2mks)
       2. Its apparent weight in a liquid of density 800kg/m³. (3mks)
    2. Figure 9 shows a cylindrical solid 20 cm long and density2400kg/m³. Its cross-section area is 6cm² and floats in water of density 1000kg/m³ while partially submerged with 10cm below the surface of water
       
       Figure 9
       Determine
       1. Weight of the solid (3mks)
       2. Upthrust on the solid (3mks)
15.  
    1. Figure 10 below shows a section of a tape pulled through a ticker timer of requency50Hz.
       
       Figure 10
       
       1. Determine the velocity of the body pulling the tape in cm/s in figure 10 above(3mks)
       2. Find the acceleration of a body in cm/s² for the tape represented in Figure 11 below.  (take the frequency as 50Hz) (4mks)
          
          Figure 11
    2. A lorry of mass 12000kg is travelling at 10m/s and is brought to rest in 20seconds
       Determine;
       1. The acceleration of the lorry (2mks)
       2. The average retarding force (2mks)
16. Two similar cans are partly filled with equal quantities of paraffin. Each holds a thermometer, is covered with a lid and stands on a wooden bench at the same distance from radiant heat as shown in Figure 12 below.
    
    Figure 12
    Container A has a dull black surface and container B has bright silvered surface. The following temperatures were recorded.
    

    Time in minutes	0	1	2	3	4	5
    Temp oC (dull black)	19	21	23	25	27	29
    Temp oC (silvered bright)	19	20	21	22	23	24

    1. Explain why heat from the heater could not have reached the cans by:-
       1. Conduction – (1mk)
       2. Convection - (1mk)
       3. Explain why there is a difference in the thermometer readings in A and B.         (2mks)
       4. How can the set-up in figure 12 above be adjusted in order to produce same reading of the thermometer. (1mk)
    2. Two beakers A and B contain equal amounts of warm water initially at 35^oC Water at 0^oC is added to beaker A while ice cubes at 0^oC are added to beaker B. Which beaker will have a lower temperature after a few minutes and why? (2mks)
    3. In an experiment to determine the specific latent heat of vaporization of water, steam at 100^oC was passed into water contained in a well lagged aluminum calorimeter. The following measurements were made;
       Mass of calorimeter = 150g
       Initial mass of water 100g
       Intial temperature of water = 18^oC
       Final mass of calorimeter + condensed steam = 275g
       Final temperature mixture 68^oC
       (Specific heat capacity of water = 4.2KJkg^-1K^-1
       And C.H.C for aluminium = 400 Jkg^-1K^-1)
       Determine;
       1. Mass of condensed steam (1mk)
       2. Heat gained by calorimeter and water (3mks)
       3. Given that Lv is the specific latent heat of vaporization of steam.
          1. Write an expression for the heat given out by steam. (1mk)
          2. Determine the value of Lv. (3mks)
17. Figure 13 below shows a hydraulic press used to lift a load L. The effort applied is 400N at the end of the lever 50cm long and pivoted at the other end.
    
    Figure 13
    The plunger is 10cm from the pivot. The area of piston A is 2.0 x 2⁻⁴ m² and that of piston B is 4.0 x 10⁻² m².
    Determine;
    1. Pressure exerted at piston A. (3mks)
    2. Weight of the load L being lifted. (3mks)
    3. If small piston moves down a distance of 10cm, determine how far upwards the longer piston B moves.  (3mks)
18.  
    1. State the differences between temperature measured in Kelvin scale and Celsius scale. (1mk)
    2. Figure 14 below shows a simple set up for pressure law apparatus.
       
       Figure 14
       
       1. State two measurements that can be recorded using the above apparatus        (2mk)
       2. Explain how the measurement above in (i) may be used to verify pressure law. (3mks)
    3. State one assumptions of real gas laws (1mk)
    4. At 20^oC the pressure of a gas is 50cm of mercury. At what temperature would the pressure of the gas fall to 10 cm of mercury. (3mks)