Physics Paper 1 Questions and Answers - Lainaku II Joint Mock Examination 2023

INSTRUCTIONS TO CANDIDATES

• This paper consists of TWO sections A and B
• Answer ALL questions in the spaces provided
• Mathematical table and electronic calculators may be used.
• ALL working MUST be shown clearly where necessary.
• Take: acceleration due to gravity g = 10m/s2

SECTION A (25 MARKS)
Attempt ALL questions in this section.

1. Name the branch of physics that deals with solar water heating system. (1 mark) 
2. Define the term “Ideal gas” as used in gas laws (1 mark) 
3. At Thompson falls water, falls through a height of 30m. Calculate the final temperature if the temperature at the top is 14°C (Take g = 10 N/kg and s.h.c of water = 4200 J/kgK) (3 marks)
4. State two conditions that must be fulfilled for a body to be in equilibrium (2 marks) 
5. The figure below shows a graph of velocity against time for a moving body.
      
   Determine the distance covered by the body during the 10 seconds (3 marks)
6. Smoke is enclosed in smoke cell and sealed. When illuminated and viewed under a microscope, it is observed to be moving in continuous random motion. State and explain the observation when cold water is poured on the smoke cell. (2 marks)
7. The pressure inside a submarine is maintained at 500m of mercury(500mHg). Determine the depth at which the submarine will be safe from implosion taking the density of water as 1.025g/cm³ and atmospheric pressure = 760cmHg. (Take the density of mercury as 13600 Kg/m³)
   (3 marks)
8. Explain why two cars are likely to crush as they travel at high velocities sideways. (2 marks)
9. When a body of mass 0.25kg is acted on by a force, its velocity changes from 5.0 m/s to 7.5m/s, determine the impulse of the force. (2 marks)
10. State two factors that affect the spring constant of springs made from the same wire. (2mks)
11. Draw a well labeled diagram of a clinical thermometer. (3 marks)
12. Differentiate between solids, liquids and gases in terms of thermal conductivity. (1 mark)

SECTION B (55 MARKS)
Attempt ALL questions in this section.

1. The figure below shows a hydraulic press supporting a load F.
             
   1. What properties of oils make them suitable for use in hydraulic machines such as the one above? (2marks) 
   2. If A and a are areas of cross-section of the pistons, and the lengths of the arm are as given, find:
      1. The force F_a (2 marks)
      2. The force F₀ (2 marks)
   3. The mechanical advantage of the machine (1mark)
   4. The velocity ratio of the machine (3 marks)
   5. State one reason why the efficiency of a pulley system is always less than 100% (1 mark)
2.  
   1. State Newton’s third law of motion. (1 mark)
   2. Distinguish between elastic and inelastic collision. (2 marks)
   3. A mini bus of mass 2000kg travelling at a constant velocity of 20m/s collides with a stationary car of mass 1000kg. The impact takes 2 seconds before the two moves together at a constant velocity for half a minute. Calculate.
      1. The common velocity (3 marks)
      2. The distance moved after impact. (2 marks)
      3. The change in Kinetic energy. (3 marks)
3.  
   1. State the law of floatation. (1 mark)
   2. The figure below shows a floating object of volume 4000cm³ and mass 10g. It is held as shown in water of density 1.25g/cm³ by a light cable at the bottom so that ¾ of the volume of the object is below the water surface ( Assume the upthrust due to air is negligible).
         
      1. Calculate the volume of the object under water. (2 marks)
      2. Calculate the weight of water displaced. (3 marks)
      3. Determine the tension in the cable. (2 marks)
      4. Calculate the density of the object. (2 marks)
   3. The diagram below shows a car acid hydrometer.
        
      1. Indicate on the diagram above the minimum and the maximum measurement to be taken. (1 mark)
      2. State the reason why
         1. The bulb is wide. (1 mark)
         2. Lead shots are used (1 mark)
4.  
   1. State what is meant by the term ‘specific latent heat of vaporization’ (1mark)
   2. In an experiment to determine the specific latent heat of vaporization of water, steam at 100°C was passed into water at 5°C contained in a well-lagged copper calorimeter. The following measurements were made;
      Mass of calorimeter 50g
      Initial mass of water 70g
      Final mass of calorimeter + water + condensed steam = 123g
      Final temperature of mixture = 30°C
      (Specific heat capacity of water =4200 Jkg⁻¹ K⁻¹, specific heat capacity for copper = 390 Jkg⁻¹ K⁻¹)
      1. Determine the:
         1. Mass of condensed steam (2 marks)
         2. Heat gained by the calorimeter and water (3 marks)
      2. Given that L is the specific latent heat of vaporization of steam, determine the value of L. (3 marks)
5.  
   1. Define the term angular velocity. (1 mark)
   2. A body of mass 5 kg is whirled horizontally making a conical pendulum as shown in the diagram below
         
      1. State what happens when the speed of whirling is increased (1 mark)
      2. If the radius of the path is 50cm and the centripetal force is 285N. Determine the linear velocity of the mass (3 marks)
   3. A stone is whirled in a vertical circle as shown in the figure below using a string of length 40 cm. A, B, C and D are various positions of the stone in its motion. The stone makes 2 revolutions per second and has a mass of 100g.
              
      1. Calculate:
         1. The angular velocity (2 marks)
         2. The tension on the string at position A (3 marks)
      2. At C where the stone has acquired a constant angular speed, the string cuts. What is the name given to the path followed by the stone? (1 mark)

MARKING SCHEME

1.	Thermodynamics	1mk
2.	These are gases that obeys all gas laws completely	1mk
3.	E = mgh     = m x 10 x 30 = 300m;  Q = mcΔƟ  300m = m x 4200 x (Ɵ – 14);  Ɵ = 14.07°C;	3mks
4.	sum of clockwise moments is equal to sum of anticlockwise moments about the same point; The sum of upward forces is equal to the sum of downward forces;	2mks
5.	Distance = Area under the curve;                  = ½ x 5 x 20 + ½ x 5 x 20;                  = 100m;	3mks
6.	The motion of the particles slows down; Lowering the temperature reduces the kinetic energy of   the particles;	2mks
7.	P = hρg;  500 x 13600 x 10 = h x 1025 x 10 + 0.76 x 13600 x 10;  h = 6624m;	3mks
8.	The particles of air in between the two cars are set at a higher velocity; This lowers the pressure   between the cars. Due to pressure difference the cars collides;	2mks
9.	Impulse = change in momentum;  = 0.25(7.5 – 5.0)  = 0.625Ns;	2mks
10.	Number of turns per unit length; diameter of the turns;	2mks
11.	Correct diagram 1mk   Correct scale 1mk   Any 2 correct labels 1mk	3mks
12.	Solids are better thermal conductors compared to liquids while liquids are better thermal   conductors than gases	1mk
13.	Oil is incompressible High boiling point and low freezing point Not corrosive (any two correct)    F1/A1 = F2/A2; Fa/0.01 = 700/0.2 Fa = 35N; F1d1 = F2d2; F0 x 1 = 35 x 0.2 F0 = 7N;  M.A = Load/Effort = 700/7 = 100; V.R1 = crossection area of Load piston            cross section area of Effort piston         = 0.20.01 = 20; V.R2 = 1/0.2 = 5; V.R. = 20 x 5 =100;   friction between movable parts The weight of the lifted parts of the machine (any correct answer)	2mks     4mks     1mk     3mks      1mk
14.	For every action force there is an equal and opposite reaction force/ Action and reaction force are equal and opposite    Elastic collision  Inelastic collision  Momentum and kinetic energy are conserved  Only momentum is conserved;  Bodies separate after collision  Bodies merge after collision;   m1u1 + m2u2 = (m1 + m2)v; 2000 x 20 + 0 = (2000 + 1000)v; V = 13.33m/s; distance = velocity x time;               = 13.33 x 30               = 399.9m; Change in K.E = ½ m1v2 – ½ m2v2;   = 0.5 x 2000 x 202 – 0.5 x 3000 x13.332;   = 133466.65J;	1mk     2mks   3mks     2mks 3mks
15.	A floating body displaces its own weight of the fluid in which it floats   volume = ¾ x 4000;              = 3000cm3; weight = upthrust = vρg;             = 3000 x 10-6 x 1250 x 10;             = 37.5N; Tension + Weight = Upthrust; Tension = 37.5 – 0.1               = 37.4N; Density = mass/volume              = 10/4000 ;               = 2.5 x 10−3g/cm3;                   both maximum and minimum;   To displace large volume of liquid providing sufficient upthrust; to enable the hydrometer float upright;	1mk    2mks 3mks        2mks           2mks     1mk     1mk 1mk
16.	Quantity of heat required to change a liquid into vapour at constant temperature     mass = 123 − 120;          = 23g; Q = mcΔƟ;     = 0.07 x 4200 x 25 + 0.05 x 390 x 25;     = 7837.5J; Q = mL; 7837.5 = 0.023L; L = 340760.9J/kg;	1mk     2mks   3mks 3mks
17.	Rate of change of angular displacement with time;   The mass is raised higher/the radius of the circular path increases/the angle increases; F = mv2 ;         r 285 = 5 x v2             0.5 ; V2 = 28.5   V = 5.339m/s;     ա = 2πf;     = 2 x 22/7 x 2     = 12.57rad/s; T = mա2r – mg;    = 0.1 x 12.572 x 0.4 – 1;    = 5.3202N; Trajectory;	1mk 1mk       3mks   2mks   3mks     1mk