Physics P1 Questions and Answers - Wisdom Pre-Mock Form 4 Exams 2021/2022

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INSTRUCTIONS TO CANDIDATES

  • Write your Name, Admission number, Class and Index Number in the spaces provided above.
  • This paper consists of two sections: A and B
  • Answer all the questions in the spaces provided
  • All working must be clearly shown.
  • Mathematical tables and electronic calculators may be used
  • Take g=10ms-2
  • Density of mercury = 13600 kg/m3

For Examiner’s Use

SECTION

QUESTION

MAXIMUM SCORE

CANDIDATE’S SCORE

A

1-13

25

 

B

14

11

 

15

11

 

16

09

 

17

12

 

 

18

12

 

TOTAL

80

 


QUESTIONS

Section A (25 marks)
Answer all the questions in the spaces provide

  1. A partially inflated balloon at sea level becomes fully inflated at higher altitudes. Explain this observation (2 marks)
  2. The figure below shows a pith ball being lifted into the funnel by blowing air into the funnel Explain this observation (2 marks)
    2 UGAYTAG
  3. State two reasons why gases diffuses at a higher rate than liquids. (2 marks)
  4. A student set up an experiment as shown below using two gas jars, one with hot coloured water, the other with cold clear water separated by a smooth card. The upper jar is upside down. Explain the observation made when the card is removed. (2 marks)
    4 kjaghuyhda
  5. The figure below shows the scale of a Vernier calipers which is closed fully. State the Zero error of the instrument (1 mark)
    5 jytdatfd
  6. The figure below shows a uniform body suspended freely through a hole on an optical pin. State with reason the case where the body is more stable (2 marks)
    6 hgffdaytfd
  7. The figure below shows a metal being heater at the middle. Giving the reason state the wax that will fall off first (2 marks)
    7 iiiguygucga
  8. The figure below shows a system with a liquid enclosed by two pistons. Equal force F is applied on the system as shown. Giving reason show with an arrow the direction of movement of the liquid (2 marks)
    8 ikgauygdua
  9. The figure below shows a bimetallic wheel whose diameter is not affected by changes in temperature. Briefly explain how the diameter of the wheel remain unchanged as the temperature increases. (2 marks)
    9 nihgaugda
  10. Two identical springs have a combined spring constant of 3.5N/cm when in series Determine combined spring constant when the springs are in parallel. (2 marks)
  11. Two coins A and B of the same mass and material are placed on a turntable as show below. The turntable is then rotated at a high speed. With reason name the coin that skids first (2 marks)
    11 jgvFGYFtdyta
  12. A substance of volume Xcm3 and density 800kgm-3 is mixed with 100cm3 of water of density 1000kgm-3. The density of the mixture is 960kgm-3. Determine the value of X. (2 marks)
  13. A bullet of mass 10g travelling at a speed of 400ms-1 hits a tree trunk. It penetrates the tree trunk and stops inside the trunk after 4 cm. Calculate the average resistance force offered by the trunk to the bullet. (2 marks)

Section B (55 marks)
Answer all the questions in the spaces provide

  1.                        
    1. A body accelerates from rest. Its velocity after 5 seconds is 26m/s and after 9 seconds its velocity is 42m/s. calculate
      1. Distance moved during the motion (3 marks)
      2. Average speed of the journey (2 marks)
    2. A car can be brought to rest from a speed of 20m/s in a time of 2s when brakes are applies.
      1. Find the average deceleration (1 mark)
      2. The car is stopped by a policeman when moving at a speed of 20m/s. If the driver’s reaction time is 0.2s determine the shortest stopping distance. (2 marks)
    3. The figure below shows the graph of a tennis ball bouncing severally on a table
      14 jhagudga
      Describe the motion between
      1. AB (1 mark)
      2. BC (1 mark)
      3. CD (1 mark)
  2.                            
    1. State the Pascal principle (1 mark)
    2. State the principal of moments (1 mark)
    3. The figure below shows a 100cm uniform bar of weight 50N balanced horizontally on two pistons.
      15 ujgyda
      Correct to 2 decimal places determine
      1. Force exerted on piston A (3 marks)
      2. Force exerted on Piston B (3 marks)
      3. Cross section area of piston A (3 marks)
  3.                                  
    1. The figure below shows 30cm3 of gas trapped in a tube containing mercury to a height of 14.5cm. The prevailing atmospheric pressure is 760mmHg. Determine the pressure acting on the gas in Pascals (3 marks)
      16 a jhvagda
    2. Determine the volume of the gas when the tube is held as shown below
      1. 16 b 1 jgvfahyfsa(3 marks)
      2. 16 b 2 agvda(3 marks)
  4.                              
    1. State the law of floatation. (1 mark)
    2. The figure below shows a block cuboid of dimensions 4cm by 4cm by 16cm floating in a liquid in an overflow can with 3/4 of its height submerged.
      17 uagydga
      Given that the mass of the beaker when empty is 85g and the reading on the scale in the set up above is 245g, calculate:
      1. The density of the block. (3 marks)
      2. The density of the liquid. (2 marks)
    3. A metal block is suspended from a spring balance and held inside a beaker without touching the beaker. Water is added gradually into the beaker. The graph below shows the variation of up thrust on the block with depth of water.
      17 c jagujyda
      Explain the shape of the graph. (2 marks)
    4. The figure below shows a pulley system being used to raise a load.
      17d jagtda
      1. Indicate the direction of the strings (1 mark)
      2. If an effort of 35N raises a load of 105N, determine the efficiency of the system.(3 marks)
  5.                                
    1. The figure below shows a car of mass (m) moving along a curved part of the road with a constant speed.
      18 ihg uygs
      1. Explain why the car is more likely to skid at Y than at X. (2 marks)
      2. If the radius of the road at V is 250m and the car has a mass of 600kg, determine the maximum speed at which the car can be driven while at V without skidding. Force of friction between the road and the tyres is 18000N. (3 marks)
    2. A string of length 70cm is used to whirl a stone in a circle in a vertical plane at 5 rev/s.
      Determine:
      1. The period (1 mark)
      2. The angular velocity. (2 marks)
      3. The speed of the stone (2 marks)
    3. A body moving in a circle with constant speed is said to have an acceleration. Explain. (1 mark)


MARKING SCHEME

Section A (25 marks)
Answer all the questions in the spaces provide

  1. A partially inflated balloon at sea level becomes fully inflated at higher altitudes. Explain this observation (2 marks)
    • At high attitutes, atmospheric pressure is lower than at the sea level
    • air in the ballon expands hence making the ballon fully inflated
  2. The figure below shows a pith ball being lifted into the funnel by blowing air into the funnel Explain this observation (2 marks)
    2 UGAYTAG
    • air passes the narrow part at a higher speed than the wider part. pressure lowers.
    • higher pressure form below pushes the ballon upwards
  3. State two reasons why gases diffuses at a higher rate than liquids. (2 marks)
    • gases have higher KE/weaker cohesion
    • gases have lower density
  4. A student set up an experiment as shown below using two gas jars, one with hot coloured water, the other with cold clear water separated by a smooth card. The upper jar is upside down. Explain the observation made when the card is removed. (2 marks)
    4 kjaghuyhda
    • hot remains on top/colour does not spread down
    • hot water has lower density than cold water hence it remains on top
  5. The figure below shows the scale of a Vernier calipers which is closed fully. State the Zero error of the instrument (1 mark)
    5 jytdatfd
    • -0.02cm
  6. The figure below shows a uniform body suspended freely through a hole on an optical pin. State with reason the case where the body is more stable (2 marks)
    6 hgffdaytfd

    • the cog is lower than the point of support
  7. The figure below shows a metal being heater at the middle. Giving the reason state the wax that will fall off first (2 marks)
    7 iiiguygucga
    • B
      it has more delocalized electrons than the thinner
  8. The figure below shows a system with a liquid enclosed by two pistons. Equal force F is applied on the system as shown. Giving reason show with an arrow the direction of movement of the liquid (2 marks)
    8 uhgaugda
    • pressure at B lowers more than at A creating pressure gradient towards B
  9. The figure below shows a bimetallic wheel whose diameter is not affected by changes in temperature. Briefly explain how the diameter of the wheel remain unchanged as the temperature increases. (2 marks)
    9 nihgaugda
    • Brass expands more than iron 
      The wheel curves more thus compensating the expansion
  10. Two identical springs have a combined spring constant of 3.5N/cm when in series Determine combined spring constant when the springs are in parallel. (2 marks)
    10 ihhauigduya
  11. Two coins A and B of the same mass and material are placed on a turntable as show below. The turntable is then rotated at a high speed. With reason name the coin that skids first (2 marks)
    11 jgvFGYFtdyta
    • A
      since F = mrw2 and mass and w are constant then Fαr
      A requires more centripetal force than friction can offer or A is at a higher speed
  12. A substance of volume Xcm3 and density 800kgm-3 is mixed with 100cm3 of water of density 1000kgm-3. The density of the mixture is 960kgm-3. Determine the value of X. (2 marks)
    12 ugvabuyga
  13. A bullet of mass 10g travelling at a speed of 400ms-1 hits a tree trunk. It penetrates the tree trunk and stops inside the trunk after 4 cm. Calculate the average resistance force offered by the trunk to the bullet. (2 marks)
    • KE = work
      1/2mv2 = F.d
      1/2 × 0.01 × 4002 = F × 0.04
      0.04F = 800
      F = 20,000N

Section B (55 marks)
Answer all the questions in the spaces provide

  1.                        
    1. A body accelerates from rest. Its velocity after 5 seconds is 26m/s and after 9 seconds its velocity is 42m/s. calculate
      1. Distance moved during the motion (3 marks)
        14 gaygdyad
      2. Average speed of the journey (2 marks)
        • speed = d/t = 201/9 = 22.33m/s
    2. A car can be brought to rest from a speed of 20m/s in a time of 2s when brakes are applies.
      1. Find the average deceleration (1 mark)
        • a = v - a     0 - 2 = -10m/s  d = 10m/s
                  t           2
      2. The car is stopped by a policeman when moving at a speed of 20m/s. If the driver’s reaction time is 0.2s determine the shortest stopping distance. (2 marks)
        • dist = 0.2 × 20 + (20 + 0) × 2 = 24
                       OR
          dist = 20 × 0.2 + 20 × 2 + 1/2(-01)(2)2 = 24
    3. The figure below shows the graph of a tennis ball bouncing severally on a table
      14 jhagudga
      Describe the motion between
      1. AB (1 mark)
        • body accelerates downwards
      2. BC (1 mark)
        • body hits the table and reverses immediately
      3. CD (1 mark)
        • body decelarating upwards
  2.                            
    1. State the Pascal principle (1 mark)
      • pressure applied at one point is transmitted throughout the other points of an enclosed liquid
    2. State the principal of moments (1 mark)
      • in balanced conditions, the sum of clockwise moments equals the sum of anticlockwise moments about the same point
    3. The figure below shows a 100cm uniform bar of weight 50N balanced horizontally on two pistons.
      15 ujgyda
      Correct to 2 decimal places determine
      1. Force exerted on piston A (3 marks)
        • moments about A 
          sum of clockwise moment = sum of anticlockwise moment
          50 × 40 = f × 85
          f = 23.53N
      2. Force exerted on Piston B (3 marks)
        • upward force = downward force
          23.53 + F = 50
          f = 26.47N
      3. Cross section area of piston A (3 marks)
        • F1F2
          A1     A2
          23.53 = 26.47
          A1         0.5     
          23.5  × 0.5
              26.47
          =0.44m2
    1. The figure below shows 30cm3 of gas trapped in a tube containing mercury to a height of 14.5cm. The prevailing atmospheric pressure is 760mmHg. Determine the pressure acting on the gas in Pascals (3 marks)
      16 a jhvagda
      • p = cp + atm
        14.5 + 76 = 90.5smHg
    2. Determine the volume of the gas when the tube is held as shown below
      1. 16 b 1 jgvfahyfsa(3 marks)
        • P1V1 = P2V2
          90.5 × 30 = 76 × V2
          V2 = 35.72cm3
      2. 16 b 2 agvda(3 marks)
        • P1V1 = P3V3
          90.5 × 30 = 61.5V3
          V3 =90.5 × 30 = 44.15 cm3
                    61.5
  3.                              
    1. State the law of floatation. (1 mark)
      • A floating body displaces its own weight of the fluid in which it floats
    2. The figure below shows a block cuboid of dimensions 4cm by 4cm by 16cm floating in a liquid in an overflow can with 3/4 of its height submerged.
      17 uagydga
      Given that the mass of the beaker when empty is 85g and the reading on the scale in the set up above is 245g, calculate:
      1. The density of the block. (3 marks)
        • mass of water drop = mass of the block
          mass of the block = 245 - 85 = 160g
          α m =           160                 160         = 0.8333g/cm3
              v     4 × 4 × 3/4 × 16       4 × 4 × 12
      2. The density of the liquid. (2 marks)
        • α m =      160         = 0.625g/cm3
              v     4 × 4 × 16
    3. A metal block is suspended from a spring balance and held inside a beaker without touching the beaker. Water is added gradually into the beaker. The graph below shows the variation of up thrust on the block with depth of water.
      17 c jagujyda
      Explain the shape of the graph. (2 marks)
      • as water is added upthrust on  the metal increases
      • when fully submerged, there is no more water is displaced hence the upthrust becomes constant
    4. The figure below shows a pulley system being used to raise a load.
      d ugyaytda
      1. Indicate the direction of the strings (1 mark)
        • SEE ABOVE
      2. If an effort of 35N raises a load of 105N, determine the efficiency of the system.(3 marks)
        • VR = 4
          MA = L = 105 = 3
                   E     35
          MA
           × 100 = Eff
          EFF = 3/4 × 100 = 75%
  4.                                
    1. The figure below shows a car of mass (m) moving along a curved part of the road with a constant speed.
      18 ihg uygs
      1. Explain why the car is more likely to skid at Y than at X. (2 marks)
        • At Y, ,the radius is shorter than at X
        • At Y , the car may require more centripetal force than friction can provide
          F = mv2 and α m and v are constant 
                  r
          therefore f α 1
                                r
      2. If the radius of the road at V is 250m and the car has a mass of 600kg, determine the maximum speed at which the car can be driven while at V without skidding. Force of friction between the road and the tyres is 18000N. (3 marks)
        • F = mv2
                  r
          18000 = 600v2
                        250
          V2 = 18000 × 250
                                 600
          V2 = 7500
          V = 86.6m/s
    2. A string of length 70cm is used to whirl a stone in a circle in a vertical plane at 5 rev/s.
      Determine:
      1. The period (1 mark)
        • T = time  for 1 Rev
          1 rev  = 1/5 = 0.25
      2. The angular velocity. (2 marks)
        • w = 2π = × 3.142 = 31.42 
                            0.2
      3. The speed of the stone (2 marks)
        • v = rw
          =0:7 × 31.42 = 21.99m/s  or 22m/s
    3. A body moving in a circle with constant speed is said to have an acceleration. Explain. (1 mark)
      • velocity charges due to change of direction of the body leading to acceleration
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