Physics Paper 1 Questions - Kassu Joint Mock Examination 2021

INSTRUCTIONS TO CANDIDATES

Write your name, admission number and index number in the spaces provided above.
Sign and write the date of examination in the spaces provided above
This paper consists of TWO sections A and B.
Answer ALL the questions in section A and B in the spaces provided.
All working MUST be clearly shown.
Non programmable silent calculators may be used.
ALL numerical answers must be expressed in decimal notation.
This paper has 14 pages. It is the responsibility of the candidate to ascertain that all the pages are printed as indicated and that no questions are missing.
Candidates should answer the questions in English.
Constant: g=10N/kg or 10m/s²

SECTION A: (25 marks)
Answer ALL the questions in this section in the spaces provided.

Figure 1 shows a magnified portion of the scale of a micrometer screw gauge used to measure the diameter of spherical object.

Figure 1
State the diameter of the object (1mark)
Figure 2 shows a flask fitted with a glass tube dipped into a beaker containing water at room temperature. The cork fixing the glass tube is air tight.

Figure 2
State with reason what is observed when the flask is held with warm hands. (2marks)
1800 cm³ of fresh water of density 1g/cm3 is mixed with 2200cm³ of sea water of density 1.03g/cm³. Determine the density of the mixture. (2marks)
1. State the principle of moments. (1 mark)
2. Figure 3 shows a uniform meter rule balancing when a mass of 200g is hung at one end. Determine the tension T in the string (2marks)
Name two forces that determine the shape of liquid drop on a solid surface. (2marks)
It was observed that when air is blown between two pieces of paper, both cling to each other. Explain. (1mark)
1. State the Hooke’s Law. (1mark)
2. Figure 4 shows identical spiral springs supporting a load of 90N. Each spring has a spring constant k = 200N/m
  
  Determine the total extension of the system (take the weight of the cross bars and springs to be negligible) (2 marks)
In an experiment to estimate the diameter of an oil molecule, an oil drop of diameter 0.05cm spreads over a circular patch whose diameter is 20cm. Determine the diameter of the oil molecule. (3marks)
Figure 5 shows a rectangular loop with two thin threads loosely tied and dipped into a soap solution.

Figure 5
Draw on the side of Figure 5 what is observed when point B is punctured. (1mark)
1. Figure 6 shows a manometer used to measure the lung pressure of a student. Given that the atmospheric pressure is 103360Pa, determine the lung pressure of the student. (2marks)
  
  Figure 6
2. State one factor affecting pressure in fluids. (1mark)
Give a reason why mass of a body is constant everywhere. (1mark)
A stop watch reads 08:12:84 and 09:10:72 before and after an experiment respectively. Determine the duration of the event in SI units. (2marks)
Explain what thermodynamics is as a branch of physics. (1 mark)

SECTION B: (55 marks)
Answer ALL the questions in this section in the spaces provided.

1. Define the term work done as applied in physics. (1mark)
  ………………………………………………………………………………………………………………………………………………………………………………………………………………
2. Figure 7 shows the cross – section of a wheel and axle of radius 6.0 cm and 1.5 cm respectively used to lift a load. Use it to answer the questions that follow.
  
  Figure 7
  Determine the:
  1. 1. mechanical advantage (M.A) of the system. (1mark)
    2. velocity ratio ( V.R) of the system. (1mark)
    3. efficiency of the machine. (1mark)
  2. Give one reason why the above machine is not 100% efficient. (1mark)
3. Define specific latent heat of vaporisation (1 mark)
4. 1200g of a liquid at 100C is poured into a well-lagged calorimeter. An electric heater rated 1.5 KW is used to heat the liquid. Figure 8 shows the variation of temperature of the liquid with time.
  
  Use figure 8 to answer the following questions:
  1. State the boiling point of the liquid (1 mark)
  2. Determine the amount of heat given out by the heater to heat the liquid to the boiling point. (2 marks)
  3. Determine the specific heat capacity of the liquid. (2marks)
  4. If 20g of the liquid vapour was collected by the end of the 8th minute, determine the specific latent heat of vaporization of the liquid. (2 marks)
1. Figure 9 shows a velocity –time graph for the motion of a certain body.
  
  Figure 9
  Describe the motion of the body in the region:
  1. OA: (1mark)
  2. AB: (1mark)
  3. BC: (1mark)
2. A car moving initially at 25m/s decelerates at 4 m/s².
  1. Determine the time taken for the car to stop (2marks)
  2. Sketch the velocity – time graph for the motion of the car up to the time the car stopped. (1mark)
3. A ball is projected vertically upwards with initial velocity of 80m/s. Determine the time taken to reach maximum height. (2marks)
4. A bullet of mass 80g moving with a velocity of 20m/s penetrates a sand bag and it’s brought to rest in 0.05 seconds. Determine average retarding force of the sand. (2marks)
5. 1. State the principle of conservation of linear momentum (1 mark)
  2. A bullet of mass 60g is fired horizontally with a velocity of 200 m/s into a suspended stationary wooden block of mass 2940g. Determine:
    1. Common velocity of both the bullet and the block, if the bullet embedded into the block. (2 marks)
    2. Height to which the block rises. (2 marks)
1. Explain why bodies in circular motion undergo acceleration even when their speed is constant. (1mark)
2. A particle moving along a circular path of radius 5cm describes an arc of length 2cm every second. Determine:
  1. Its angular velocity. (1mark)
  2. Its periodic time. (2marks)
3. A stone of mass 150g is tied to the end of a string 80cm long and whirled in a vertical circle at 2rev/s. Determine the maximum tension in the string. (3marks)
4. State one factor affecting centripetal force (1mark)
1. State the Archimedes’ principle. (1 mark)
2. The weight of a stone in air is 8.5N. When fully immersed in paraffin of density 0.8g/cm³ its weight is 7.3N. Determine the;
  1. up thrust in the paraffin. (1 mark)
  2. volume of the stone. (2 marks)
3. Figure 10 shows rectangular metal block of density 12,500kgm-3 and dimensions 30cm x 20cm x 20cm suspended inside a liquid of density 1200kgm-3 by a string attached to appoint above the liquid. The three forces acting on the block are; the tension T, on the string, the weight W, of the block, and the up thrust, U, due to the liquid.
  
  Figure 10
  1. Write an expression relating T, W and U when the block is in equilibrium inside the liquid. (1 mark)
  2. Determine the weight, W, of the block (1 mark)
  3. Determine the weight of the liquid displaced by the fully submerged block (2 marks)
  4. Hence determine the tension, T, in the string (1 mark)
1. Figure 11 shows a set-up that may be used to verify pressure law.
  
  Figure 11
  1. State the measurements that should be taken in the experiment. (2 marks)
  2. Explain how the measurements in (i) above may be used to verify pressure law. (2 marks)
2. A column of air 26cm long is trapped by mercury thread 5.0cm long as shown in figure11 (a) . When the tube is inverted as in figure11 (b) the air column becomes 30cm long. Determine the value of atmospheric pressure (2 marks)
  
  Figure11
3. A steel cylinder of capacity 0.45m³ contains nitrogen at a pressure of 40,000Pa when the temperature is 17ºC. Determine the pressure of nitrogen if it is allowed to flow into another cylinder of capacity 8.5m³ with the temperature reduced to -23ºC. (2 marks)
4. Using kinetic theory of gases, explain how a rise in the temperature of a gas causes a rise in its pressure if the volume is kept constant. (2 marks)