Physics Paper 1 Questions and Answers - Mathioya Mock Exams 2022

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INSTRUCTION TO CANDIDATES.

  •  This paper contain two sections; Section A and Section B
  • Answer all the questions in section A and B, In the spaces provided
  •  Marks may be given for correct working even if the answer is wrong.
  • Calculators and KNEC Mathematical tables may be used EXCEPT where stated otherwise.
  • Show all the steps in your calculations, giving your answers at each stage in the spaces below each question.

SECTION A: (25 MARKS)

  1. Sketch a graph of volume of paraffin against temperature when heated from 0°C to 10°C (2 marks)
    Phycp1q01
  2. State two reasons why diffusion is more rapid in gases than in liquids. (2 marks)
  3. A trolley of mass 20kg moving at 0.8m/s on frictionless horizontal surface was acted upon by a force of 2.5N. After impact the body moves at 4.8m/s. Determine the time of impact of the force. (3 marks)
  4. The diagram below shows a metal tube made of iron and copper. The joint is tight at room temperature.
    Phycp1q04
    Explain how you would separate the two by changing the temperature given that copper expands more than iron for same change in temperature. (2 marks)
  5. The figure below shows a system in equilibrium with the horizontal level.
    Phycp1q05
    AB is an uniform rule of length 1.0m and weighs 20N.
    Calculate
    1. Weight of the block X (3 marks)
    2. Tension in the string PQ (1 mark)
  6. The figure below shows parts A, B and C of a glass tube
    Phycp1q06
    State with a reason the part of the tube in which the pressure will be lowest when air is blown through the tube from A to C. (2 marks)
  7. The mass of an empty density bottle is X g. When full of water its mass is 70g and 68.4g when full of another liquid L whose density is 0.96g/cm3. Determine the value of X.(Density of water is 1g/cm3) (3 marks)
  8. The figure below shows a simple apparatus used to measure atmospheric pressure at sea-level.
    Phycp1q08
    State what will happen to the value of h if;
    1. The apparatus is taken to the top of a mountain (1 mark)
    2. Some air is introduced in the space above the mercury in the glass tube. (1 mark)
    3. The glass tube is tilted a little. (1 mark)
  9. An air bubble at the bottom of a beaker full of water becomes larger as it rises to the surface. State the reasons why.
    1. The bubble rises to the surface (1 mark)
    2. It becomes larger as it rises (1 mark)
  10. When a solid is heated, its volume increases. Explain the effect on its density. (2 marks)

SECTION B: (55 MARKS)

  1.      
    1. A body of a given mass was projected vertically upwards. Explain the factor that will determine time taken to reach maximum height. (2 marks)
    2. A tape attached to a moving trolley is run through a ticker timer. The figure below shows a section of the tape after running.
      Phycp1q11b
      If the frequency of the ticker timer is 100Hz.
      Determine the
      1. Average velocity at interval
        1. AB (2 marks)
        2. CD (2 marks)
      2. Acceleration of the trolley. (2 marks
    3. A car is brought to rest from a velocity of 100m/s in 4 seconds.
      1. Determine the average acceleration (2 marks)
      2. If the driver’s reaction time is 0.1 seconds, determine the shortest stopping distance. (3 mks)
  2.  
    1. State Hooke’s Law. (1 mark)
    2. A spring is made of a steel wire of a given thickness and length. State two factors that will determine its spring constant. (2 marks)
    3. Three identical springs each of spring constant 10N/m and weight 0.5N are used to support a load as shown. Ignore the weight of the connecting rods.
      Phycp1q12c
      Determine the total extension produced. (3 marks)
    4. A set of identical springs are arranged as shown below.
      Phycp1q12d
      On the same axes sketch a force (N) against extension (m) for the two sets and label them as (a) and (b). (2 marks)
  3.     
    1. The figure below shows a body of mass 20kg placed on an inclined surface AB. It is allowed to slide down the incline from B to A.
      Phycp1q13a
      State two factors that will determine the magnitude of the velocity at which the mass will be moving at as it reached A. (2 marks)
    2. The wheel and axle in the figure below is used by well diggers to raise soil from the pit. The axle has a diameter of 12cm.
      Phycp1q13b
      The 50kg of soil is raised through a distance of 10m, when an effort of 100N is applied on the handle.
      Calculate
      1. The mechanical advantage of the system (2 marks)
      2. The velocity ratio of the system (2 marks)
      3. The efficiency of the wheel and axle system (3 marks)
    3. A body of mass 20kg hangs 4m and swings through a vertical height of 0.9m as shown in the figure below.
      Phycp1q13c
      Determine
      1. The potential energy at its highest point. (1 mark)
      2. The speed of the body when passing through the lowest point. (3 marks)
  4.    
    1. Define the term heat capacity. (1 mark)
    2. A 180W heater is immersed in a copper calorimeter of mass 100g containing 200g of alcohol. When the heater is switched on for 4 minutes the temperature of the calorimeter and its contents raises by 72°C. (Specific heat capacity of copper=400J/kgK)
      Calculate
      1. The amount of heat energy supplied by the heater in the 4 minutes (2 marks)
      2. The specific heat capacity of alcohol (2 marks)
    3. State two differences between boiling and evaporation. (2 marks)
    4. State three ways of increasing the sensitivity of a liquid - in – glass thermometer. (3 marks)
  5.   
    1. State the Law of floatation (1 mark)
    2. The figure below shows a cork floating on water and held to the bottom of the beaker by a thin thread.
      Phycp1q15b
      1. Indicate on the figure the forces acting on the cork. (3 marks)
      2. Describe how each of the forces mentioned in (i) above changes when water is added into the beaker untill it fills up. (3 marks)
    3. The weight of a solid in air is 5.0N. When it is fully immersed in a Liquid of density 800kg/m3. Its weight is 4.04N. determine
      1. The upthrust in the Liquid (1 mark)
      2. The density of the solid (3 marks)

Marking Scheme

  1.  
    Phycp1qa01
    Axes labelled (1 mk)
    Shape (straight line) (1mk)
  2.          
    • The particles of gases have lower density than particles of liquids.
    • Particles of gases have higher kinetic energy than particles of liquids.
    • Gases have lower cohesive force than liquids.
      Any two
  3. Impulse = change in momentum
    Ft = mv – mu (1mk)
    t =mV-mU
             F
    = 2O(4.8-0.8) (1mk)
             2.5
    = 32 seconds (1mk)
  4.     
    • Lowering the temperature(cooling) at the joint (1 mk)
    • Copper will contract at a higher rate than iron. (1mk)
  5.     
    1. sum of clockwise moments = sum anticlockwise moments (1mk)
      X x 40 + 20 x 10 = 80 x 40 (1 mk)
      40 X + 200 = 3200
      40X = 3000
      X = 75N (1mk)
    2. Sum of Upward forces=sum of downward forces at equilibrium
      75 + 20 + 80 = 175 N (1mk)-Transfer of error allowed)
  6. point B (1mk)
    • The velocity is highest at this point hence pressure decreases. (1mk)
  7. mass of water = 70 – x
    Volume of water = m
     70 - x  
           1
    = 70 - x
    Volume of liquid L = 70 – x (1mk)
    ρ =M/V
    0.96 =    68.4 -  x   (1mk)
                     70 -x
    0.96(70 – x) = 68.4 – x
    67.2 – 0.96x = 68.4 – x
    X – 0.96x = 68.4 – 67.2
    0.04x = 1.2
    X = 30 cm3 (1mk)
  8.      
    1. Decrease (1mk)
    2. Decrease (1mk)
    3. No change. (1mk)
  9.       
    1. air (in the) bubble is less dense than water. (1mk)
    2. Pressure reduces as the bubble rises due to decrease in liquid depth hence expands (temperature is constant) (1mk)
  10.   
    1. Density lowers/decreases (1mk)
    2. Mass remains constant (1mk)
  11.   
    1. initial velocity (U) (1mk)
      The higher the initial velocity, the higher the time taken. Or the lower the initial velocity, the lower the time taken. (1mk)
    2.      
      1. T = 1/f
        = 1/100
        = 0.01 seconds
        1. VAB = 1.50.01 X 3 (1 mk)
          = 50 cm/s (1mk)
          OR 0.5 m/s
        2. VCD = 3.30.01 X 3 ( 1mk)
          = 110 cm/s
          OR 1.1 m/s
      2. a =    V-U   
                   t
           110   -       50
          0.01 X 3 X3
        = 666.67 cm/s2
        OR 6.667 m/s2
    3.    
      1. a =    V  -   U  
                  t
        = 0  -  100 (1mk)
                 4
        = - 25 m/s2 (1mk)
      2. S =ut + ut + ½ at2 (1mk)
        = 0.1 X 100 + 100X 4 – ½ X 25 X 4 X 4(1mk)
        = 10 + 200
        = 210 m (1mk)
  12.      
    1. For a helical spring or any other elastic material the extension is directly proportional to applied force provided the elastic limit is not exceeded.(1mk)
    2.    
      • number of turns per unit length. (1mk)
      • Diameter of the spring. (1mk)
        Note: Other factors already stated in the stem of the questio
    3. F= ke (1mk)
      extension = 7/10 + 3/10 (1mk)
      = 0.7 + 0.3
      = 1.0 m (1mk)
    4.      
      Phycp1qa12d   
  13.          
    1.         
      • height/length of the inclination or Angle (θ) of inclination
      • Nature of the surface/friction between the surfaces. (Smoothness or roughnessof the surfaces)
        Any two
    2.    
      1. M.A = LoadEffort
        = 50 X 10 (1 mk)
             100
        = 5 (1mk)
      2. V.R =Rr
        = 50/6 (1mk)
        = 8.333 ( 1mk)
      3. n =M.A/V.R X 100 ( 1 mk))
        = 5/8.333 X 100 (1mk)
        = 60.00% ( 1mk)
    3.   
      1. P.E = mgh
        = 20 X 10 X 0.9
        = 180 J ( 1 mk)
      2. P.E lost = K.E gained ( 1mk)
        180 = ½ X 20 X V2 ( 1mk)
        V2 =   180 X 2
                    20
        V = √18
        = 4.243 m/s (1mk)
  14.  
    1. Amount of heat required to raise the temperature of a given mass of a substance by one degree Celsius or one kelvin. (1mk)
    2.   
      1. H = pt
        = 180 X 4 X 60 ( 1 mk)
        = 43,200 J ( 1mk)
      2. pt = mc X cc X ∆θ + mA X cA X ∆θ ( 1mk)
        43,200 = 100/1000 X 400 X 72 + 200/1000 X cA X 72 ( 1mk)
        43,200 = 2880 + 14.4 cA
        14.4 cA= 40,320
        CA= 2,800J/kgK ( 1mk)
    3.   
       BOILING  EVAPORATION
       Takes place at a fixed temperature  Takes place at all temperatures
       Takes place throughout the liquid (with bubbles of steam formed)  Takes place on the surface of the liquid (with no bubbles formed)
       Decreasing atmospheric pressure lowers the boiling point  Decreasing atmospheric pressure increases the rate of evaporation
      Any two
    4. making the bore narrower
      making the wall of the bulb thinner
      increasing the size of the bulb
      using a liquid with a higher rate of expansion
      Any three
  15.  
    1. a floating body displaces its own weight of the fluid in which it floats. (1mk)
    2.      
      1.   
        Phycp1qa15bi
      2. Upthrust - increase (1 mk)
        Weight- remains constant (1 mk)
        Tesion - increase (1mk)
    3.      
      1. Upthrust = weight in air - weight in liquid
        = 5.0 – 4.04
        = 0.96 N (1mk)
      2. U = Vρg
        0.96 = V x 800 x 10 (1mk)
        V =0.96/8000
        = 1.2 X 10-4 m3
        ρ = m/V
        m = W/g
        m =5/10
        = 0.5 kg
        ρ =0.5/0.00012 ( 1 mk)
        = 4,166.67 kg/m3 (1 mk)
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