Physics Paper 3 Questions and Answers - Arise and Shine Pre Mock Exams 2023

INSTRUCTIONS TO CANDIDATES

• Answer ALL the questions in the spaces provided.
• You are supposed to spend the first 15 minutes of the 2 ½ hours allowed for this paper reading the whole paper carefully before commencing your work.
• Marks are given for a clear record of the observations actually made, their suitability, accuracy and the use made of them.
• Candidates are advised to record their observations as soon as they are made.
• KNEC MATHEMATICAL TABLES AND NON PROGRAMMABLE SILENT CALCULATORS MAY BE USED.

For Examiners’ Use Only

QUESTION 

QUESTION 1
You are provided with the following apparatus.

• An ammeter (range 0 – 1A)√
• A resistance wire labeled R√
• Two new dry cell (size D) √
• Six connecting wires (at least three with crocodile clip) √
• A switch√
• A jockey√
• A micrometer screw gauge (to be shared) √
• A voltmeter (0-3V) √
• Proceed as follows:

1. Assemble your apparatus as shown in Figure 1
   
2. With the switch S open, record the voltmeter reading.
   
   V = ……………………. Volts (1 mark)
3. Adjust the length x of the wire to 25cm. Close the switch, read and record the value of current I in Table 1
   Table 
   

   Length x (cm)	25	35	45	55	65	75
   Length (100 – x) cm
   Current I (A)
   .  (A-1)

4. Repeat (c) for other values of x given in Table 1. Complete the table. (5 marks)
5. On the grid provided plot a graph of length (100-x) m against 1/I (A^-1) (5 marks)
   
6. calculate the slope S of the graph (3 marks)
7. what does the y-intercept represent? (1 mark)
8. Using the micrometer screw gauge provided measure the diameter t, of the resistance wire R
   t = ………………………………………mm (2 marks)
   t = ………………………………………..m
9. Given P = SVt²/4
   Determine the value of P (3 marks)

QUESTION 2

This question has two parts A and B. Answer all the parts

Part A
You are provided with the following:

• A metre rule√
• Two identical 100g masses (labelled A and B) √
• Liquid L in 250ml beaker ¾ full √
• Three pieces of thread, each 30cm long. √
• Stand with clamps√
• Tissue paper√
• Vernier calipers√

Proceed as follows:

1. Take one 100g mass and measure the diameter d and height h using the Vernier calipers
   d = …………………………. M (1 mark)
   h = …………………………. M (1 mark)
2. Determine the volume V given that V = π (d/22)2h
   V ……………………………….m³ (1 mark)
3. Using a stand and one piece of thread, suspend the metre rule in air such that it balances horizontally.
   Record the position of the centre of gravity G.
   G = ………………………………………………..cm (1mark)
   NOTE: the metre rule should remain suspended at this point throughout the experiment.
4. Set up the apparatus as shown in Figure 1 below;
   
   
   • Suspend the mass A at a distance x = 30cm and completely immerse it in liquid L without touching the sides of the beaker.
   • Hang mass B and adjust its position such that the rule is balanced and measure the distance dcm. Tabulate your results in table 1 below;
     1. Table (3 marks)
        

        x (cm)	30	35	40
        d (cm)

5.               
   1. Determine the weight F of one of the masses A or B in air. Given that
      g = 10N/K g and A = B
      Weight F in air = …………………………………….. (1 mark)
   2. Using the principle of moments, determine the apparent weight P of A when completely immersed in Liquid L
      Apparent weight P = …………………………………………………………………………(2 marks)
   3. Find the up thrust U on A when completely immersed. (1 mark)
   4. Upthrust; U = .......................................................................................................................................
6.          
7.            
8. Determine the density of liquid L, given that; (1 ½ marks )
   P = Un/V where n = 0.1 Kg/N (1 ½ marks)

PARTTWO
You are provided with the following apparatus

• A glass beaker√
• A metal solid√
• Some water√
• Source of heat√
• A piece of cotton thread√
• A plastic beaker wrapped with tissue√
• Thermometer√
• Liquid L√

Proceed with the experiment as follows:
(f). Fill the glass beaker with the water provided and place it on the fire source. Use the piece of thread to carefully lower the metal solid to the bottom of the beaker.
Heat the water to its boiling point. Use the thermometer to measure its boiling point.
Boiling point of water …………………………….Kelvin (1 mark)

(g).

1. Find the following measurements using appropriate instruments
   Mass of the solid Ms = …………………………………g (1/2 mark)
   Mass of the wrapped empty plastic beaker M1 ……………..g (½ mark)
   
   Use the plastic beaker to measure 240ml of liquid L, hence find the joint mass of the plastic beaker and its content liquid L,
   M2 = ………………………………………….(g) ( ½ mark)
   : Initial temperature of liquid L, T1 = ………………………Kelvin (1 mark)
2. At boiling point of water; quickly transfer the metal solid into liquid L, stir well and measure the temperature of the mixture immediately.
   Temperature of the mixture T2 ……………………..Kelvin (1 mark)

(h). By using the measurements taken in pars (f) g(i) and g(ii) as well as the equation provided below, determine the specific heat capacity of liquid L. (Take S.H.C of metal solid = 480J/kg/k and S.H.C of plastic = 359 J/kg/k).
(Heat lost by metal) = (heat gained by liquid L) + (heat gained by plastic beaker). (3 marks) 

MARKING SCHEME

QUESTION 1
You are provided with the following apparatus.

• An ammeter (range 0 – 1A)
• A resistance wire labeled R
• Two new dry cell (size D)
• Six connecting wires (at least three with crocodile clip)
• A switch
• A jockey
• A micrometer screw gauge (to be shared)
• A voltmeter (0-3V)

Proceed as follows:

1. Assemble your apparatus as shown in Figure 1
2. With the switch S open, record the voltmeter reading.
   V = 3.10. Volts (1 mark)
3. Adjust the length x of the wire to 25cm. Close the switch, read and record the value of current I in Table 1
   

   Length x (cm)	25	35	45	55	65	75
   Length (100 – x) cm	75	65	55	45	35	25
   current I (A)	0.13	0.15	0.17	0.21	0.26	0.34
   (A-1)	7.692	6.667	5.882	4.762	3.846	2.941

4. Using the micrometer screw gauge provided measure the diameter t, of the resistance wire R
   • t = 0.37mm
     t = 0.37x10^-3m
     1. Given P = SVt²/4
        Determine the value of P (3 marks)
        P = 1.588 x 10^-1 x 3.0 x (0.37x10^-3)² =1.6305 x 10^-8 (with or without units
                                                       4

QUESTION 2
This question has two pars A and B. Answer all the parts

Part A
You are provided with the following:

• A metre rule
• Two identical 100g masses (labelled A and B)
• Liquid L in 250ml beaker ¾ full (water)
• Three pieces of thread, each 30cm long.
• Stand with clamps
• Tissue paper
• Vernier calipers

Proceed as follows:

1. Take one 100g mass and measure the diameter d and height h using the Vernier calipers
   d = 3. dp m - Accept any-measurements of masses not specified (1mark)
   h = 3.dp m (1 mark)
2. Determine the volume V given that V = π(d/2) 2_h
   V Exact or 4.s.fm³ (1 mark)
3. Using a stand and one piece of thread, suspend the metre rule in air such that it balances horizontally.
   Record the position of the centre of gravity G.
   G = 50.0 ±1dpcm (1mark)
   NOTE: the metre rule should remain suspended at this point throughout the experiment.
4. Set up the apparatus as shown in Figure 1 below;
   
   Suspend the mass A at a distance x = 30cm and completely immerse it in liquid L without touching the sides of the beaker.
   • Hang mass B and adjust its position such that the rule is balanced and measure the distance dcm. Tabulate your results in table 1 below;
     1. Table (3marks)
        

        x (cm)	30	35	40
        d (cm)	26.0	31.0	35.0	- ALL 2 correct @ ½  mrk 0.5
        	Exact or 4 s.f			-          ALL 2 correct @ ½ mrk

5.                
   1. Determine the weight F of one of the masses A or in air. Given that g = 10N/K g and A = B
      Weight F in air = 1N√1 Ignore Unit but penalize fully if the unit is wrong (1 mark)
   2. Using the principle of moments, determine the apparent weight P of A when completely immersed in Liquid L
      1 x d = WX correspond value of x√
      1 x 26 = w x 30
   3. Apparent weight P = 0.8667√1 - Ignore units but penalize fully if wrong units given . Find the up thrust U on A when completely immersed. (1 mark)
   4. Upthrust; U = Answer @ e- Answer (a) F√½
      = Exact √1/2 - Ignore unit but penalize fully if unit is wrong
6.                          
7.          
8. Determine the density of liquid L, given that;
   P = Un/V where n = 0.1 Kg/N (1 ½ marks)
   Answer @ g x 0.1
       Answer @ b
   = Exact or 4.s.f- ignore unit but penalize fully if unit is wrong

PART TWO
You are provided with the following apparatus

• A glass beaker
• Aa metal solid
• Some water
• Source of fire
• A piece of cotton threadA plastic b
• eaker wrapped with tissue
• Thermometer
• Liquid L

Proceed with the experiment as follows:
(f). Fill the glass beaker with the water provided and place it on the fire source. Use the piece of thread to carefully lower the metal solid to the bottom of the beaker.
Heat the water to its boiling point. Use the thermometer to measure its point.

• Boiling point of water = (91+273) Kelvin (1 mark)

(g).

1. Find the following measurements using appropriate instruments
   Mass of the solid Ms = 62.23 g (1/2 mark)
   Mass of the wrapped empty plastic beaker M1 ……………..g (½ mark)
   Mass of plastic beaker + water = 271.24g
   T1 (Cold H²O) - T1 = 22ºC + 273
   T2 (Hot water) - 91+273
   Metal inside (final temp of mixture)
   T3 = 24ºC+273
2. heat cost by metal solid = heat gained by cold water + heat gained by plastic beaker
   0.06323x480x67= (0.03561x359x2) +0.23563x9x2
   2033.4768 = 25.56798+0.47126CL.
   CL =(2007.9088)/(0.47126)
   = 42.60Jkg-1k-1± 300
   
   Use the plastic beaker to measure 240ml of liquid L, hence find the joint mass of the plastic beaker and its content liquid L, M² = (Hot water) - 91+273(g) ( ½ mark)
   
   : Initial temperature of liquid L, T1 = (Cold H2O) - T1 = 22oC + 273Kelvin (1 mark)

(b)(ii). At boiling point of water; quickly transfer the metal solid into liquid L, stir well and measure the temperature of the mixture immediately.

• Temperature of the mixture T2(Hot water) - 91+273Kelvin (1 mark)

(c). By using the measurements taken in pars (f) g(i) and g(ii) as well as the equation provided below, determine the specific heat capacity of liquid L. (Take 5.H.C of metal solid = 480J/kg/k and 5.H.C of plastic = 359 J/kg/k).

• (Heat lost by metal) = (heat gained by liquid L) + (heat gained by plastic beaker). (3 marks) 

CONFIDENTIAL

Physics teachers to ensure the following apparatus are provide.

QUESTION ONE

• An ammetre (range 0-1A)
• A resistance wire labelled R 28Gw or d = 0.36mm
• Two new dry cell (size D) and a cells holder
• Six connecting wires at least 3 with crocodile clips at the ends
• A switch
• A jockey
• A micrometer screw gauge (to be shared)
• A voltmeter (0-3V)

QUESTION TWO

PART A

• A metre rule
• Two identical 100g masses (labelled A and B)
• Liquid L in 250ml beaker, ¾ full (water)
• Three pieces of thread, each 30cm long
• Stand with clamps
• Tissue paper
• Vernier calipers (to be shared)
• A glass beaker (500ml)
• Metal solid (pendulum bob of about 65g)
• Some water
• Source of Heat
• A piece of cotton thread (30cm)
• A plastic beaker wrapped with tissue paper on the outside
• Liquid L (water)