# Physics Paper 1 Questions and Answers - Catholic Diocese of Kakamega Mock Exams 2023

INSTRUCTIONS TO CANDIDATES:

1. This paper consists of two sections A and B.
2. Answer all questions in Section A and B in the spaces provided.
3. All working MUST be clearly shown in the spaces provided.
4. Non-programmable silent electronic calculators may be used.
5. Candidates should answer the questions in English.

SECTION A: 25 MARKS
Answer all questions in this section

1.
1. Draw a diagram to represent a scale of a micrometer screw gauge of thimble scale 50 divisions and reading 3.68mm
(2mks)
2. Determine the actual reading if the micrometer screw gauge above has a zero error of 0.03mm. (1mk)
2. Figure 1 shows a bimetallic strip made of brass and iron. A marble is placed at end of the bimetallic strip
as shown below:-

State and explain what will be observed when the bimetallic strip is strongly cooled
(2mks)
3. A bottle containing a smelling gas at the front bench of a classroom is opened. State the reason why the gas is detected throughout the room
(1mk)
4. Figure 2 shows the level of mercury and water in a beaker.

Explain the difference in the shape of the meniscus
(Imk)
5. Mercury - in glass barometer shows a height of 70cm. What height would be shown in the barometer at the same place if water of density 1.0 x 103kg/m3 is used. (Density of mercury = 13600kgm3) (2mks)
6. The figure below shows a beaker containing a block of ice.

State and explain the change in stability when the ice melts.
(2mks)
7. Figure 3 shows a uniform rod AB which is 40cm long. It has a mass of 2kg and pivoted at C. If 2N is
acting at point B, and 30N force is passed through a frictionless pulley.

Find the force X acting at end A.
(3 marks)
8. Sketch on the axis provided below a velocity - time graph of a motion of a stone thrown vertically upward from the edge of a platform and eventually the stone lands without bouncing on the ground below the platform.

(1 mark)
9. Figure 4 shows two light sheets of paper arranged as shown.

Explain what is observed if strong air is blown at the same time behind paper Q and in front of paper R as shown
(2mks)
10. State and explain a branch of physics that involves the study of sound.
(2mks)
11. State two physical quantities that remain constant while pure ice is being converted to water. (2mks)
12. State the reason why thermal conductivity of a metal increases with increase in the cross-section area of the conductor?
(1mk)
13. State two factors that lower surface tension of water.
(2mks)
14. On the grid provided, sketch a graph of mechanical advantage against load for a pulley system used to

(1 mk)

SECTION B (55 MARKS) (Answer all the questions)
15.
1. State two ways in which the freezing point of ice can be lowered
(2mks)
2. The figure below illustrates an experiment in which electrical energy is used to determine specific latent heat of fusion.

1. Complete the circuit to show the essential circuit components.
(2mks)
2. Write down an equation showing how quantities measured from the above set -up can be used to determine the latent heat of fusion of ice.
(1mk)
3. A block of metal of mass 150g at 100°C is dropped into a lagged calorimeter of heat capacity 40JK-1 containing 100g of water at 25°C. the temperature the resulting mixture is 34°C. (specific heat capacity of water is 4200 JKg-1K-1)
Determine;-
1. Heat gained by the colorimeter
(2mks)
2. Heat gained by water
(2mks)
3. Specific heat capacity of the metal block.
(3mks)
16.
1. One of the factors that affect the centripetal force is the mass of the body. State another factor.
(1mk)
2. A mass of 400g is rotated by a string at a constant speed V in a vertical circle of radius 100cm. the
tension in the string experienced at point T is 9.2N.

1. Determine the velocity V of the mass at point T.
(3mks)
2. Determine the tension in the string at the bottom of the circle.
(2mks)
3. State two applications of circular motion.
17.
1. State the Archimedes principle.
2. A rubber envelope of a hydrogen filled balloon having volume of 2m3 is held in position by a vertical
string as shown below.

The mass of the balloon is 1.3kg. Given that density of hydrogen is 0.1kg/mand density of air is 1.3kg/m3.
Calculate
1. The total weight of the balloon including the hydrogen gas.
(2mks)
2. The up thrust.
(2mks)
3. The tension in the string
(2mks)
3.  A solid weighs 50N in air and 44N when complete immersed in water. Calculate
1. Relative density of the solid.
(2mks)
2. Density of the solid.
(Imk)
18.
1. Define velocity ratio as used in machines.
(1mk)
2. The figure below shows a pulley system used to lift a load of 1200N using an effort of 400N

1. State the velocity ratio of the system
(1mk)
2. State the function of pulley D.
(1mk)
3. Indicate the direction of tension force in each string.
(1mk)
3.  The figure below shows an inclined plane. A trolley of mass 30kg is pulled up a slope by a force of 100N parallel to the slope. The trolley moves so that the centre of mass C travels from points A to B.

1.  What is the work done on the trolley against the gravitational force in moving from A to B?
(2mks).
2. Determine the work done by the force in moving the trolley from A to B.
(2mks)
3. Determine the efficiency of the system.
(3mks)
4. Determine the mechanical advantage of the system.
(2mks)
19.
1. What is meant by absolute zero temperature?
2. The set up below was used by a group of form three students to verify pressure law.

Describe briefly how the set-up can be used to verify pressure law.
(1mk)
(4mks)
3. A 4.5cm3 bubble released at the bottom of a dam measured 18cm3 at the surface of the dam. Work out the depth of the dam taking atmospheric pressure to be 1 x 105 Pa and the density of water as 1g/cm3
(3mks)
4.
1. What is meant by the term "ideal gas".
(1 mk)
2. A container holds 70cm3 of air. The pressure is 100kPa and the temperature is 7°C. What is the final pressure when the air is compressed to 30cm3 and the temperature is 27°C.     (3 mks)

MARKING SCHEME

SECTION A (25 MARKS)

1.
1. 3.68-0.03
= 3.65mm
2. Marble rolls down towards the middle because brass contracts more than iron
3. Because of diffusion.
4. Adhesive forces between water molecules and glass beaker are stronger than cohesive forces between water molecules hence resultant force makes water to form a concave meniscus. Cohesive forces between mercury molecules are greater than adhesive forces between mercury molecules and glass beaker hence resultant force makes mercury form a convex meniscus.
5. 0.7 x 13600 x 10 = h x 1000 x 10
h = 9.52m
6. It becomes more stable because the position of centre of gravity is lowered.
7. For a system in equilibrium; Moment = Fd
Sum of clockwise moments = sum of anticlockwise moments.
(30x02) + (2x0.1) = (20x0.1) + (x x 03)
6.2-2=0.3x
X = 14N
8. The papers bulge outwards away from each other. This is due to the pressure outside reducing below atmospheric pressure hence resultant outward force.
9. Waves - The study of propagation of energy through space.
(2mks)
10.
• Temperature
• Mass
11. Increase in cross-section area increases the number of free electrons per unit length which are
responsible for thermal conductivity.
• increase in temperature
12.
1.
• decreasing pressure
2.
1. Vit = mLf
3.
1. θ = C θ
= 40 x (34-25)
= 360J
2.  Q = mcθ
= 100 x10-3 x 4200 x (34-25)
= 3780J
3. Heat lost = Heat gained
Heat lost 360 + 3780 = 4140J
MCθ = 4140
C = 4140
150 x 10-3 x (100-34)
= 418.18J/kgK
13.
1.
• angular velocity
2.
1. T =  mv− mg
r
9.2 = 0.4v2 − 4
1
V2 = 9.2 + 4
0.4
V = 5.745m/s
2. T = mv2 + mg
1.          r
= 0.4 x 5.7452 + 4 = 17.2N
1
3.
• Merry go round
• Speed governors
• centrifuge
• satellites
14.
1. When a body is partially or totally immersed in a fluid, it experiences an up thrust equal to the weight of the fluid displaced.
2.
1. W = mg + Pvg
= (1.3 x 10) + (2x0.1x10)
= 15N
2. U = weight of the fluid displaced
U = vpg
U = 2 x 1.3 x 10
U=26N
3. T=U - W
= 26 -  15
9N
3.
1. RD    weight of solid
upthrust
= 50
(50-44)
= 8.333

2. Density R.d x density of water
= 8.333 x 1
= 8.333g/cm3
15.
1. ratio of the distance moved by the effort to the distance moved by the load.
2.
1.  4
2. To change the direction of the effort.

3.
3.
1. W = F x d
2. =  300 x 10
= 3000J
3. W = F x d
= 100 x   10
Sin 15
= 3863.7J
4. r = work output x 100%
work input
3000   x 100%
3863.7
= 77.65%
1. M.A.= L
= 300
100
= 3
16.
1. Temperature at which the volume of a gas is assumed to be zero.
2. Record the initial temperature and pressure.
• Heat the water bath gently
• record the temperature and corresponding pressure at regular intervals of temperature say 10°C.
• tabulate the results for pressure and absolute temperature.
• draw a graph of pressure against absolute temperature
• the graph is a straight line through the origin with a positive gradient.
This shows that the pressure is directly proportional to absolute temperature.
3. P1V1 = P2V2
(105+ h x 1000 x10) 4.5 x 10-6  = 105 x 18 x 10-6
h = 30m
4.
1. An ideal gas is the gas that obeys all the gas laws completely.
2. P1V1 = P2V2
Ti         T2
100 X 70 = P2 X 30
280            300

P2 = 250kPa

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