Physics Paper 1 Questions and Answers - Lanjet Mock Exams 2021/2022

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INSTRUCTIONS TO CANDIDATES

  • This paper consists of two sections, Section A and B.
  • Answer ALL the questions in section A and B in the spaces provided.
  • ALL answers and working MUST be clearly shown.
  • Mathematical tables and electronic calculators may be used.
  • Take acceleration due to gravity, g = 10m/s2
  1. Figure 1 below shows a micrometer screw gauge being used to measure the diameter of a metal rod. The thimble scale has 50 divisions.
    Phys LJM PP1 Q1 2122
    Find the diameter of the metal rod. (1 mark)
  2. Explain briefly how the temperature in a green house is kept higher than outside. (2 marks)
  3. The diagram shown in figure 2 below is an arrangement of three pulley wheels used to help in lifting loads. Use it to answer questions 3 and 4.
    Phys LJM PP1 Q3 2122
          Fig. 2
    Complete the diagram to show how the rope goes round the wheels, position of the load and the effort. (2 marks)
  4. Write down the velocity ratio (VR) of the system. (1 mark)
  5. State how temperature affects the speed of sound in air. (1 mark)
  6. State two facts which show that heat from the sun does not reach the earth surface by convection. (2 marks)
  7. The diagram in figure 3 below shows water with negligible viscosity flowing steadily in a tube of different cross-section area. If at a point A, the cross section area is 120cm2 and the velocity of water is 0.40ms-1, calculate the velocity at B where cross section area is 4.0cm2? (3 marks)
    Phys LJM PP1 Q7 2122
  8.  A motor uses an electrical energy at a rate of 200W and raises a mass of 25kg through a vertical distance of 20m in 0.5 minutes. Determine the efficiency of the motor. (3 marks)
  9. Name three types of forces that act between bodies not in contact. (3marks
  10. How long will it take 240V, 3000W electric immersion heater to raise the temperature of 150 litres of water in a well-lagged calorimeter made of copper of mass 20kg from 15° to 70°C? (3 marks)
  11. The diagram shown in the Figure 4 below shows a system in equilibrium with the rule horizontal.
    AB is a uniform rule of length 1.0m and weight 1.8N. Calculate the weight of the block X. (3 marks)
    Phys LJM PP1 Q11 2122
  12. State the reason why a trailer carrying heavy loads has many wheels. (1 mark)

SECTION B (55 MARKS)
Answer ALL the questions

  1.  The figure 5 below shows the displacement – time graph of the motion of particlePhys LJM PP1 Q13 2122
    1. State the nature of the motion of the particle between
      1. A and B (1mk)
      2. B and C (1mk)
      3. C and D (1mk)
    2. A ball is thrown horizontally from top of a vertical tower and strikes the ground at a point 50 m from the bottom of the tower. Given that the height of the tower is 45m, determine the
      1. Time taken by the ball to hit the ground. (2m)
      2. Initial horizontal velocity of the ball (2mks)
      3. Vertical velocity of the ball just before striking the ground. (2mks)
        ( take acceleration due to gravity gas 10m/s)
  2.  
    1. State the pressure law; (1 mark)
    2. Explain how a gas exerts pressure. (2 marks)
    3. The figure below shows a set up used to verify pressure law.
             Phys LJM PP1 Q14c 2122
      1. State the measurement that may be taken in the experiment. (2 marks)
      2. Explain how the measurement in (i) above may be used to verify pressure law. (2 marks)
      3. A car tyre is at pressure of 5.0x105 Pa at a temperature of 37℃. While it is running the temperature rises to 75℃. What is the new tyre pressure? (Assume the tyre does not expand) (3 marks)
  3.  
    1. Distinguish between inelastic and elastic collisions. (2 marks)
    2. The diagram in Figure 6 below shows a sphere moving in a viscous liquid in a tall measuring cylinder.
               Phys LJM PP1 Q15b 2122
      1. Show on the diagram the forces acting on the sphere. (3 marks)
      2. Sketch a graph showing the variation of velocity with time in figure 7 below. Show on the graph the terminal velocity, VT. (2 marks)
        Phys LJM PP1 Q15c 2122
  4. A mass of 1kg is attached to a cord of length 50cm. It is whirled in a circle in a vertical plane at 10 revolutions per second as shown in the figure 8 below.
              Phys LJM PP1 Q16 2122
    1. Find the tensions in the cord when the mass is at:
      1. Highest point of the circle A. (2 marks)
      2. Lowest point of the circle B. (2 marks)
    2. The diagram below shows a spring tied to an object, m, and rotated in a circular path of radius, r.
            Phys LJM PP1 Q16b 2122
      1. What provides the force that keeps the object moving in a circular path. (1 mark)
      2. The speed of the object is constant but the body is accelerating. Explain.   (1 mark)
      3. If the object is whirled faster, what would happen to spring balance reading? (1 mark)
      4. Give a reason for your answer in b(iii) above. (1 mark)
      5. As the object is whirled round the string snaps and cuts off. Describe the subsequent path of the object.
        (1 mark)
  5.  
    1. State the law of floatation. (1 mark)
    2. Figure 9 shows a piece of cork held with a light thread attached to the bottom of a beaker. The beaker is filled with water.
                  Phys LJM PP1 Q17b 2122
      1. Indicate and label on the diagram the forces acting on the cork. (1 mark)
      2. Write an expression showing the relationship between the forces above. (1 mark)
    3. A solid displaces 8.5cm3 of liquid when floating in a certain liquid and 11.5cm3 when fully submerged in the same liquid. The density of the solid is 0.8g/cm3. Determine:-
      1. The upthrust on the solid when floating. (2 marks)
      2. The density of the liquid. (2 marks)
      3. The upthrust on the solid when fully submerged. (2 marks)
  6. The following results were obtained in a experiment to verify Hooke’s law when a spring was extended by hanging various loads on it.
     Load (N)   0.00   1.00   2.00   3.00   4.00   5.00   6.00 
     Length of spring in cm   10.00   11.50   13.00   14.50   16.00   18.00   24.00 
     Extension  0.00            
    1. Complete the table for the extension e above. (1mk)
    2. Plot a graph of load (y-axis) against extension (5mks)
    3. From the graph determine the spring constant. (2mks)
    4. Calculate the energy stored when the spring is stretched to 16 cm. (2mks)


MARKING SCHEME

  1. 16.21mm✔1 correct answer with correct units
    Accept 1.621cm or 0.01621m
  2. Roofing materials allows radiations to penetrate into the greenhouse✔1 but not out. Higher concentration of carbon dioxide inside the greenhouse helps to retain higher temperature by trapping/ insulating✔1 the heat.'
  3.  
    Phys LJM Q4 Pp1 2122
  4. V.R = 3✔1
  5. Increase in temperature increases✔1 the speed of sound.
  6.  
    1. Convection takes place in air upwards direct due to✔1 to density defect.
    2. Convection requires a ✔1 material medium but the space between the sun and the earth i.e. space of the atmosphere has no material medium
  7. From the equation of continuity
    A1U1 = A2U2 ✔1(flow rate is constant)
    120 × 0.4 = 4 × U2
    ∴ U2 = 120 ×0.4 ✔1
                      4
    = 12 ms-1✔1
  8. Work done on the mass
    = force × distance
    = 25 × 10 × 120
    = 5000J. ✔1
    Work done = power × time
                       = 200 × 30✔1
                       = 6000J✔1
    But = work output ×100
               work input
    = 5000 × 100
       6000
    = 83.3% ✔1
  9.  
    • Magnetic force
    • Electrostatic force
    • Gravitational force
  10. ΔH = MCΔθ
    = 150 × 1000 × 4200 × (70 −15) + 390 × 20 × (70 −15)
      1000
    = 34650.000 + 429000
    = 463650✔1
    Energy dissipation E = pt
    3000 ×t=4636501
    ⇒t = 463650 = 154.55 sec✔1
               3000
  11. At balance
    Sum of clockwise = sum of anti-clockwise moments
    (180/1000 × 100) × 40 = 30 × X + (10 × 1.8) ✔1
    1.8 × 40 = 30X +18
    X = 1.8 × 40−18 ✔1
                   30
       = 1.8N✔1
  12. To increase surface area of contact thus reducing pressure exerted on the road✔1
  13.  
    1.  
      1. A and B - stationary body
      2. B and C -  move with increasing velocity
      3. C and D -  decreasing velocity
    2.  
      Phys LJM PP1 Ans13b 2122
      1. R = Ut
        h = ½ gt2
        45 = ½ x 10 x t2
        t2 = 45 = 9
                5
        t = 3less
      2. R = ut
        50 = 0 x 3
         3        3
        U = 50 = 16. 67 m/s
                3
      3. V = u + at
            = gt
        = 10 x 3
        =30m/s

  14.  
    1. The pressure of a fixed mass of gas is directly proportional to absolute temperature provided that volume is kept constant. ✔1
    2. When a gas is heated it expands ✔1 increasing the number of collusions per unit area which in turn raise the pressure✔1
    3.  
      1.  
        • Temperature of water✔1
        • Pressure gauge reading✔1
      2.  
        • Collect various values of pressure under different temperatures✔1
        • Plot a graph of pressure against temperature and study the values✔1
      3. P α T → P = KT → K = P/T
        P1 – 5.0 x 105 Pa
        P2 = ?
        T1 = 273 + 37 = 300k
        T2 = 75 + 273 = 348k
        P₁ = P₂
        T₁    T₂ 
        50000 P₂ 
           300     348 ✔1
        P2 = 500000 ×348
                         300
              = 580000
        P2 = 5.8 x 105 Pa✔1
  15.  
    1.  
      • Inelastic collision – K.E and momentum of the objects are conserved✔1
      • Elastic collision – only momentum is conserved✔1
    2.  

      1. Phys LJM PP1 Ans15b 2122
      2.   
        Phys LJM Q15b PP1 2122
  16.  
    1.  
      1. ω = 2πf
            = 2π × 10
            = 20πrad s-1
            = 62.83 rad-1
        TA = Mω2r – mg
            = 1 × 62.832 × 0.5 − (1×10)✔1
            = 19 + 3.9 – 10
            = 1963.9N✔1
      2. At the lowest point
        Fc = T – Mg
        ⇒ Fe + Mg
        = mr ω2 + mg
        = 1 × 0.5 × 62.832 + 1×10✔1
        = 1973.9 + 10
        = 1983.9N✔1
    2.  
      1. Tension in the spring supporting the object. ✓¹
      2. There is change in the direction of instantaneous velocity at various points along the circular path. ✓¹
      3. The spring balance reading increases. ✓¹
      4. The centripetal force
      5. The object moves tangentially to the circular path at that point where it cuts. ✓¹
  17.  
    1. A floating object displaces its own weight of the fluid in which it floats.
    2.  
      1.  
        Phys LJM PP1 Ans17bi 2122 
      2. U = mg + T
    3.  
      1. Upthrust = weight of solid
        = 11.5 x 0.8 x 10
                   1000
        = 0.092 N
      2. Density of solid = volume submerged
        Density of liquid      Total volume
        0.8 =  8.5  
        e1     11.5
        e1 = 1.0824g/cm3
        Alternatively
        e = m
               v
        = 0.092 x 100
                  8.5
        = 1.0824g/cm3 
      3. Upthrust = weight of liquid displaced
                       = 11.5 x 1.0824 x 10 1000
                        = 0.1245 N
  18.  
    1.   
       Load (N)   0.00   1.00   2.00   4.00   5.00   6.00 
       Length of spring in cm   10.00   11.50   13.00   16.00   18.00   24.00 
       Extension  0.00   1.50  3.50    6.00    8.00  14.00 
    2. Suitable axes labelled ✔1
      All points correct ✔1
      Suitable line ✔1
    3. Springs constant K =  ςF ✔1
                                         ςe
      Use students graph
      Correct units ✔1
    4. Energy stored when the length is stretched by 16 cm
      Area under the graph ✔1
      Or E = ½ ke2
      Use k from graph and e = 16 cm.
      K must be correct.
      Correct substitution ✔1
      Answer correct unit ✔1

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