Physics P1 Questions and Answers - Butula Sub-County Post Mock Exams 2021/2022

INSTRUCTIONS TO CANDIDATES

1. Write your index no in spaces provided.
2. This paper consists of two sections A and B
3. Answer all questions in the spaces provided
4. Non-programmable calculators and mathematical tables may be used
5. Show all your workings

QUESTIONS

SECTION A (25 MARKS)
Answer all questions in this section.

1. Figure 1 shows air flowing through a pipe of non-uniform cross-sectional area. Two pipes A and B are dipped into the liquid as shown.
   
   
   1. Indicate the levels of the liquid A and B. (1mk)
   2. Explain the answer in 11 (a) above. (1mk)
2. A block of copper of mass 2kg and specific heat capacity of 400J/kg/K initially at 121ºC is immersed in water at 20ºC. If the final temperature is 21ºC, determine the mass of water. (Specific heat capacity of water is 4200J/kg/k) (3mks)
3. Sketch a graph of velocity against time of a steel ball which is dropped to fall through glycerine in a measuring cylinder (2mks)
4. State one advantage of a force pump over lift pump. (1mk)
5. Name two forces that determine the shape of an oil drop on a table. (2mks)
6. When hot tea is simultaneously poured into thick glass and thin glass of similar material, the thick glass is more likely to crack. Explain the observation. (2mks)
7. Some water in a tin can was boiled for some time. The tin can was then sealed and cooled. After sometime it collapsed. Explain this observation (2mks)
8. The figure below shows a uniform Metre rule pivoted at 30cm mark. It is balanced by weight of 2Nsuspended at the 5cm mark.
   
   Determine the weight of the meter rule (3mks)
9. The figure below shows tow identical containers with water at different levels.
   
   State and explain which container is stable. (2mks)
10. The figure below shows a mass of 200g connected by a string through a hollow tube to mass of 0.5kg. The 0.5kg mass is kept stationary in the air by whirling the 200g mass round in a horizontal circle of reading 1.0metre
    
    Determine the angular velocity of the 200g mass (3mks)
11. State reason why heat transfer by radiation is faster than by conduction (1mk)
12. A body is projected vertically upwards from the top of a building. If it lands on the base of the building, sketch the velocity time graph for the motion (2mks) 

SECTION B: 55 MARKS
Answer all questions in this section.

13.                            
    1. Distinguish between latent heat of fusion and specific latent of fusion. (1mk)
    2. Figure 8 shows a block of ice. A thin copper wire with two heavy weights hanging from its ends-passes over the block. The copper wire is observed to pass through the block of ice without cutting it in a process known as regelation.
       
       
       1. Explain this observation, (3mks)
       2. What would be the effect of replacing the copper wire with a cotton thread? (1mk)
       3. Explain. (2mks)
    3. Figure 9 shows one method of measuring the specific latent heat of fusion of ice. Two funnels A and B, contain crushed ice at 0°C.
       
       The mass of melted ice from each funnel is measured after 11 minutes. The results are shown below.
       Mass of melted ice in A = 24g
       Mass of melted ice in B = 63g
       1. What is the reason for setting up funnel A? (1mk)
       2. Determine the:
          1. Quantity of heat supplied by the heater. (2mks)
          2. mass of ice melted by the heater. (1mk)
          3. specific latent heat of fusion of ice. (2mks)
14.                        
    1. State any one form of energy (1mk)
    2. An electric crane lifts a load of 2000kg through a vertical distance of 3.0m in 6 seconds
       Determine:
       1. The work done (2mrks)
       2. The power developed by the crane. (2mrks)
       3. The efficiency of the crane if it is operated by an electric motor rated 12.5kw. (2mrks)
    3. A bob of mass 20g is suspended using a string 4m long from a support and swung through a vertical height of 0.9m as shown in figure 9 below.
       Fig. 9
       
       Determine;
       1. The potential energy of the bob at its position shown. (2mrks)
       2. The speed of the bob when passing through the lowest point during the swing. 2mks
15.                                        
    1. State Hooke’s Law (1mrk)
    2. The diagram below shows a graph of force against extension for a certain spring.
       
       
       1. What is the spring constant of the spring? (2 marks)
       2. What force would cause two such springs placed side by side to stretch by 10cm. (2mrks)
    3. The three springs shown below are identical and have negligible weight. The extension produced on the system of springs is 20cm.
       
       Determine the constant of each spring. (2mks)
16.                            
    1. State what is meant by an ideal gas. (1mk)
    2. The pressure acting on a gas in a container was changed steadily while the temperature of the gas was maintained constant. The value of volume V of the gas was measured for various values of pressure. The graph shows the relation between the pressure, p, and the reciprocal of volume 1/V.
       
       
       1. Suggest how the temperature of the gas could be kept constant. (1mk)
       2. Given that the relation between pressure P and the volume V of the gas is given by: PV = k, where k is constant, use the graph to determine the value of k. (3mks)
       3. What physical quantity does k represent? (1mk)
       4. State one precaution you would take when performing such an experiment. (1mk)
    3. A gas occupies a volume of 4000 litres at a temperature of 37ºC and normal atmospheric pressure. Determine the new volume of the gas if it heated at constant pressure to a temperature of 67ºC. (Normal atmosphere pressure p = 1.01 x 10⁵pa) (3 marks)
17. The figure below shows a metal sphere of mass 400kg and volume 0.6m3 fully submerged in sea water of density 1030kg/m³
    
    Determine;
    1. The tension in the cable holding the sphere. (4mks)
    2. The radius of the sphere. (2mks)
    3. The weight of a solid in air is 5N. When it is fully immersed in a liquid of density 800kg/m3 its weight is 4.04N. Determine;
       1. The upthrust of the liquid. (1mk)
       2. The volume of the solid. (2mks)
18. A small drop of oil has a volume 5x10^-10m³ when it is put on surface of some clean water it forms a circular film of0.02m²in area.
    1. Describe how the oil patch /film is formed. (2mks)
    2. Why does the film form into a circular shape (1mk)
    3. What in the size of a molecule of oil? (3mks)

MARKING SCHEME

SECTION A (25 MARKS)
Answer all questions in this section.

1. Figure 1 shows air flowing through a pipe of non-uniform cross-sectional area. Two pipes A and B are dipped into the liquid as shown.
   
   
   1. Indicate the levels of the liquid A and B. (1mk)
      level higher in B than A
   2. Explain the answer in 11 (a) above. (1mk)
      air flow in B at higher speed have lower air pressure atmospheric pressure pushes level higher than in B
2. A block of copper of mass 2kg and specific heat capacity of 400J/kg/K initially at 121ºC is immersed in water at 20ºC. If the final temperature is 21ºC, determine the mass of water. (Specific heat capacity of water is 4200J/kg/k) (3mks)
   McCcDθ = MwCwDθ
   2 × 400  × (121 - 21) = Mw  × 4200  × (21 - 20)
   Mw = 2  × 400  × 100
              4200  × 1
   =19.05Kg
3. Sketch a graph of velocity against time of a steel ball which is dropped to fall through glycerine in a measuring cylinder (2mks)
   
4. State one advantage of a force pump over lift pump. (1mk)
   can draw water beyond 10m
5. Name two forces that determine the shape of an oil drop on a table. (2mks)
   cohesive and adhesive force
6. When hot tea is simultaneously poured into thick glass and thin glass of similar material, the thick glass is more likely to crack. Explain the observation. (2mks)
   glass is a poor thermal conductor; thick glass experiences unequal expansion
7. Some water in a tin can was boiled for some time. The tin can was then sealed and cooled. After sometime it collapsed. Explain this observation (2mks)
   steam drives away air; at first the steam pressure balances atmospheric pressure; when steam condenses, the pressure in can is below atmospheric pressure
8. The figure below shows a uniform Metre rule pivoted at 30cm mark. It is balanced by weight of 2Nsuspended at the 5cm mark.
   
   Determine the weight of the meter rule (3mks)
   F1D1 = F2D2
   2 × 25 = W × 20
   W = 50/20
   =25N
9. The figure below shows tow identical containers with water at different levels.
   
   State and explain which container is stable. (2mks)
   A; lower c.o.q
10. The figure below shows a mass of 200g connected by a string through a hollow tube to mass of 0.5kg. The 0.5kg mass is kept stationary in the air by whirling the 200g mass round in a horizontal circle of reading 1.0metre
    
    Determine the angular velocity of the 200g mass (3mks)
    mg = mass²Y
    0.5 × 10 = 0.2 × w² × 1
    w² = 0.5 × 10
                0.2
    w = √25
    w = 5 rads^-1
11. State reason why heat transfer by radiation is faster than by conduction (1mk)
    heat at radiation travelling is a wave whose speed is 3 × 10⁸ while conduction is by electron movement
12. A body is projected vertically upwards from the top of a building. If it lands on the base of the building, sketch the velocity time graph for the motion (2mks) 
    

SECTION B: 55 MARKS
Answer all questions in this section.

13.                            
    1. Distinguish between latent heat of fusion and specific latent of fusion. (1mk)
       latent heat of fusion is the amount of heat energy required to change a given mass substance from solid to liquid without change in temperature.
       specific latent heat of fusion in the amount of heat energy required to change a unit mass of a substance from solid to liquid without change in temperature.
    2. Figure 8 shows a block of ice. A thin copper wire with two heavy weights hanging from its ends-passes over the block. The copper wire is observed to pass through the block of ice without cutting it in a process known as regelation.
       
       
       1. Explain this observation, (3mks)
          hanging weight exerts pressure on ice beneath it making it to melt at a lower temperature to its melting point; water formed flows over the wire and solidifies immediately since it is no longer under pressure; as it solidifies latent heat of fusion is released and conducted by copper wire to melt the ice below
       2. What would be the effect of replacing the copper wire with a cotton thread? (1mk)
          cotton thread does not cut through the ice
       3. Explain. (2mks)
          cotton is a poor conductor of heat and cannot conduct latent heat of fusion released by solidifying ice
    3. Figure 9 shows one method of measuring the specific latent heat of fusion of ice. Two funnels A and B, contain crushed ice at 0°C.
       
       The mass of melted ice from each funnel is measured after 11 minutes. The results are shown below.
       Mass of melted ice in A = 24g
       Mass of melted ice in B = 63g
       1. What is the reason for setting up funnel A? (1mk)
          to determine mass of ice that melts due to room temperature
       2. Determine the:
          1. Quantity of heat supplied by the heater. (2mks)
             H = pt
             =24 × 11 × 60
             =15840J
          2. mass of ice melted by the heater. (1mk)
             mass = 63 - 24
             =399
          3. specific latent heat of fusion of ice. (2mks)
             pt = mlf
             15840 = 39 × lf
                          1000
             lf = 406,153.8J/kg
14.                        
    1. State any one form of energy (1mk)
       kinetic energy
       potential energy
       electrical energy
       sound
       light
    2. An electric crane lifts a load of 2000kg through a vertical distance of 3.0m in 6 seconds
       Determine:
       1. The work done (2mrks)
          workdone = mgh
          = 2000 × 10 × 3
          =60,000J
       2. The power developed by the crane. (2mrks)
          p = workdone
                   time
          =60000
                6
          =10,000w
       3. The efficiency of the crane if it is operated by an electric motor rated 12.5kw. (2mrks)
          % = poutput × 100%
                 pinput
          = 10 × 100%
            12.5
          = 80%
    3. A bob of mass 20g is suspended using a string 4m long from a support and swung through a vertical height of 0.9m as shown in figure 9 below.
       Fig. 9
       
       Determine;
       1. The potential energy of the bob at its position shown. (2mrks)
          pξQ = mgh
          = 20 × 10 × 0.9
          1000
          =0.18J
       2. The speed of the bob when passing through the lowest point during the swing. 2mks
          pξ = KE
          1/2pmo² = 0.18
          1/2 × 0.2 × o² = 0.18
          = √18
          =4.24ms^-1
15.                                        
    1. State Hooke’s Law (1mrk)
       for a helical spring or any elastic material the stretching force is directlyt proportional to extension produced as long as elastic limit is not exceeded
    2. The diagram below shows a graph of force against extension for a certain spring.
       
       
       1. What is the spring constant of the spring? (2 marks)
          k = slope
          = 1 - 0 n
             4 - 0 cm
           = 0.25Ncm^-1
       2. What force would cause two such springs placed side by side to stretch by 10cm. (2mrks)
          combined k = 0.25 × 2
          = 0.50Ncm^-1
          f = ke
          = 0.5 × 10
          =  5 cm
    3. The three springs shown below are identical and have negligible weight. The extension produced on the system of springs is 20cm.
       
       Determine the constant of each spring. (2mks)
       total extension = 20cm
       extension of each spring = 10cm
       R = E = 20N = 2Ncm^-1
              e    10cm
16.                            
    1. State what is meant by an ideal gas. (1mk)
       a gas that obeys all the gas laws
    2. The pressure acting on a gas in a container was changed steadily while the temperature of the gas was maintained constant. The value of volume V of the gas was measured for various values of pressure. The graph shows the relation between the pressure, p, and the reciprocal of volume 1/V.
       
       
       1. Suggest how the temperature of the gas could be kept constant. (1mk)
          doing experiment in open air/ allowing the compressed air temperatureto adjust back to room temperature
       2. Given that the relation between pressure P and the volume V of the gas is given by: PV = k, where k is constant, use the graph to determine the value of k. (3mks)
          k = slope
          = (2.5 - 0) 10⁵ Dc
             (3 - 0) 106 m^-3
          = 0.83 pam³
       3. What physical quantity does k represent? (1mk)
          temperature
       4. State one precaution you would take when performing such an experiment. (1mk)
          mass of gas should be kept constant
    3. A gas occupies a volume of 4000 litres at a temperature of 37ºC and normal atmospheric pressure. Determine the new volume of the gas if it heated at constant pressure to a temperature of 67ºC. (Normal atmosphere pressure p = 1.01 x 10⁵pa) (3 marks)
       v1 = v2
       t1     t2
       4000 = v2
       310     340
       v2 = 4387.1 litres
17. The figure below shows a metal sphere of mass 400kg and volume 0.6m3 fully submerged in sea water of density 1030kg/m³
    
    Determine;
    1. The tension in the cable holding the sphere. (4mks)
       T = u - w
       =vfg - mg
       = 0.6 × 1030 × 10 - 400 × 10
       = 2180w
    2. The radius of the sphere. (2mks)
       v = 4πr³
             3
       0.6 = 4πr³
                3
       = 0.767 m
    3. The weight of a solid in air is 5N. When it is fully immersed in a liquid of density 800kg/m3 its weight is 4.04N. Determine;
       1. The upthrust of the liquid. (1mk)
          upthrust  = weight of liquid displaced
          5 - 4.04 = 0.96N
       2. The volume of the solid. (2mks)
          v solid = vliquid displaced
          0.96 = v × 800 × 10
          v = 0.96
               8000
          =1.2 × 10^-4m³
18. A small drop of oil has a volume 5x10^-10m³ when it is put on surface of some clean water it forms a circular film of0.02m²in area.
    1. Describe how the oil patch /film is formed. (2mks)
       the oil floats on water since its less dense than water. It spread out into a film to form a monolayer.
    2. Why does the film form into a circular shape (1mk)
       the point where the oil chops reduces in surface tension. The adjacent regions shrinks pulling the oil patch equally in all directions
    3. What in the size of a molecule of oil? (3mks)
       vol of drop = vol of patch
       5 × 10^-10 = 0.02 × t
       t = 5 × 10^-10
            0.02
       = 2.5 × 10^-8m

CONFIDENTIAL

Question one
You are provided with the following:

• A micrometer screw gauge (to be shared)
• A vernier caliper (to be shared)
• Glass rod (diameter= 0.8 cm ± 0.1)
• A 50 cm nichrome wire SWG 28 labeled M
• Some cello tape
• One 50 g mass
• Some masses (totaling 40g)
• A meter rule
• A stand boss and clamp
• A stop watch

Question two
You are provided with the following:

• A candle
• Metre rule
• White screen
• Lens holder
• Convex lens of focal length 15 cm .
• A voltmeter ( 0-3 or 0-2.5or 0-5)
• An ammeter( 0-1)
• A nichriome wire labeled x mounted on a millimeter scale SWG 32
• 8 connecting wires with crocodile clips
• Micrometer screw gauge
• A switch
• A jockey
• One new dry cell and a cell holder.