## Physics Paper 1 Questions and Answers - Bondo Mocks 2021 Exams

QUESTIONS
SECTION A (25 marks)
Answer all questions in this section in the spaces provided

1. It is believed that the Sun goes around the earth in a circular orbit continuously. State the branch of Physics that studies this.(1 mark)
2. The figure below is the scale of vernier callipers when the jaws are fully closed without an object between.

The instrument above is used to measure the diameter of an object of radius 1.24cm. Write down the reading expected from this instrument. (2 marks)
3. A wooden block on a horizontal surface is pulled by a constant horizontal force T as shown in the diagram below, at two different sections. The block moves with constant velocity along XY. Section XYP is rough, while PQ is smooth. Use the information to answer questions that follow.
1. Describe the motion of the block as it enters section PQ. (1 mark)
4. Two identical well lagged cans A and B, each has equal volumes of water and are fitted with thermometers TA and TB as shown in the figure below. Water in A is at 45ºC, while water at B is at room temperature of 25ºC. Cold water is poured carefully in A and simultaneously, an equal mass of hot water is poured in B.
1. State which of the thermometers record a lower reading after a short while(1 mark)
5. A stone of mass 200g is whirled on a vertical circle at constant speed of 3m/s, as shown in the diagram below.

Determine the tension T in the string when the stone is at its uppermost point shown, given that the string is 40cm long. (3 marks)
6. Below is a solid frustrum of a cone, resting on its narrow end on a horizontal flat surface. The solid is made of a uniform material.

1. Name the state of equilibrium of the solid on the surface. (1 mark)
2. Locate the centre of gravity of the cone, and mark it M (2 marks)
7. Some pollen grains were placed in water to study Brownian motion in liquids. State and explain the nature of the observed motion.(2 marks)
8. When estimating the diameter of an oil molecule, a student measured the diameter of an oil drop using vernier callipers. State the assumption she made in this measurement. (1 mark)
9. A form one student at Upper Secondary School had a tin can half filled with water, as shown in the figure below.

She heated the water and let it to boil for some time. The open top was then sealed, and cold water poured on the can. The can was observed to crash in. State why:
1. The water was let to boil for some time. (1 mark)
2. Cold water was poured on the can. (1 mark)
3. Explain why the tin can crushed in (2 marks)
10. The temperature if a gas in a container of fixed volume was gradually lowered, and the corresponding pressure measured. Below, is a sketch graph showing the variation of pressure with temperature from the experiment.

1. Define temperature X using kinetic theory of matter (1 mark)
2. State the reason why temperature X cannot be achieved  (1 mark)
11. A steel wire of length 20cm was coiled several times to make a spring. The spring was loaded with various weights and a graph of Force against extension plotted as indicated in Fig I below.

State any two changes that could be made on the spring to obtain the graph in Fig II (2 marks)

SECTION B (55 marks)
Answer all the questions in this section in the spaces provided

1.
1. State Bernoulli’s principle.(1 mark)
2. In deriving the equation of continuity, it is assumed that the fluid is non-viscous. Explain the effect of increase in fluid viscosity on the type of flow. (2 marks)
3. The figure below shows water in a horizontal tube of two different sections, AB and BC.

The cross-sectional area on the piston is 1.5cm2 while that of section BC is 2.0mm2. If the piston moves 12cm from A to B in 3 seconds, calculate:
1. The volume flux of water  (3 marks)
2. The speed of water through section BC    (2 marks)
4. Below is a cross-sectional diagram of a carburettor used to supply petrol for combustion in a car engine

Explain how this carburettor is able to draw petrol into the combustion cylinders   (3 marks)
2.
1. A covid vaccine is only suitable when stored at a temperature of -40ºC. A nurse had a choice of measuring the temperature of this vaccine using either a mercury thermometer or an alcohol thermometer. Explain which of the two thermometers would be suitable.(1 mark)
2. Below is a glass flask fitted with a tube and inverted in water.

The temperature of the surrounding is slowly lowered.
1. State the observation on the liquid level in the glass tube(1 mark)
2. Give a reason for the above observation (2 marks)
3. You have been provided with the following apparatus:
A glass bulb filled with mercury fitted onto a hollow stem, ice, boiling water in a can and a grid of equal squares. Use this apparatus to describe an experiment to make a graduated thermometer whose scale is in Celsius.(4 marks)
3.
1. Define velocity ratio as used in machines (1 mark)
2. The figure below shows a load of mass 20kg being pulled up an inclined plane with a constant force of 150N. The plane makes an angle of 32ºC with the horizontal, and a height of 3m.

Determine:
1. The work done on the load(2 marks)
2. Work done by the effort(2 marks)
3. The efficiency of the system (2 marks)
4. The work done against the friction between the plane and the block (1 mark)
4.
1. Distinguish between heat capacity and latent heat of fusion of a substance (1 mark)
2. Below is a figure showing a common refrigerator used for domestic purposes. A volatile liquid circulates in the capillary tubes.

1. State the reason why the diameter of the capillary tube is made wider at the freezing compartment. (1 mark)
2. Explain the function of the compression pump. (2 marks)
3. Give a reason why food items are placed below the widened copper tube (1 mark)
3. In an experiment to determine specific latent heat of vaporization of water, steam of mass 12g at 100ºC was passed into 80g of water initially at 23ºC in a container of negligible heat capacity. The temperature of water rises by 74K. Use the information to determine specific latent heat of vaporization of water (take specific heat capacity of water as 4.2kJ/kg/K and boiling point of water as 100ºC).  (4 marks)
5.
1. The figure below shows a weighing balance on which a beaker containing some water is placed. The reading of the weighing balance and the spring balance are initially 2.80N and 2.70N respectively.

1. The metal block is gradually lowered into water. State the observation made on:
1. The spring balance reading    (2 marks)
2. The reading of the spring balance when the block is fully submerged in water is 2.36N. Determine the:
1. Reading of the weighing balance    (2 marks)
2. The density of the stone    (2 marks)
2. Below is a figure showing a hydrometer floating in water.

1. State the function of the following: (2 marks)
1. Wide bulb
2. Salt solution is added to the water. State the observation made on the hydrometer.   (1 mark)
6. A metal ball of mass 20kg at rest is pulled by a force and moves along a horizontal friction compensated table as shown below. The pull is withdrawn when the ball is at P after travelling 16 seconds from Q.

Below is a velocity-time graph for the motion of the ball as it moves along the tabletop.

1. Determine the distance PQ travelled along the tabletop.    (3 marks)
2. Calculate:
1. The average acceleration between time t = 8 seconds and t = 16 seconds (2 marks)
2. The average force acting between t = 8s and t = 16s.(2 marks)
3. From P the ball falls to the ground a distance 22.5m from the foot of the table. Calculate the height of the table.(3 marks)

## MARKING SCHEME

1. Mechanics; 1mk
2. Zero error = -0.03cm;
3. The block accelerates/velocity increases with time; 1mk
4. The block is acted upon by a net force due to a decrease in friction at PQ; 1mk
5.
1. Thermometer TB;
2. Cold water in A easily gain heat by convection unlike in B / cold water is denser thus sinks to the bottom of A, raising its temperature while in B hot water is less dense hence remains at the top maintaining the temperature at the top; 2mks
6. T + mg = mv2/r;
T= mv2/r -mg
=0.2 x 3 x 3/0.4 -0.2 x 10;
= 4.5 - 2 = 2.5N; 3mks
7.
1. Stable equilibrium;
2.
diagonals; M shown; 3mks
8. Pollen grains are in a state of continuous random motion; due to uneven bombardment/collision by the invisible water particles/molecules; 2mks
9. The drop is perfectly spherical; 1mk
10.
1. To expel air from the can;
2. To condense steam back to water; 2mks
11. A partial vacuum is created inside the can on pouring cold water reducing pressure within the can; greater pressure outside/atmospheric pressure acting from outside forces the can to crash in; 2mks
12.
1. The temperature at which the kinetic energy of a gas particles is assumed to zero/pressure of an ideal gas is zero.
2. The gas would liquefy/solidify before attaining this temperature ; 2mks
13. increase in the number of turns/coils per unit length;
making the coils of the spring wider/larger diameter; 2mks
25MARKS
14.
1. if the fluid is incompressible, non-viscous and its flow is streamline, an increase in velocity lead to a corresponding decrease inits pressure; 1mk
2. As the viscous drag increases, particles in a line of flow changes direction, eventually setting in turbulent flow from streamline flow. 2mk
3.
1. Volume flux = volume/time;
= 1.5 x 12/3;
= 6 cm3/s ; 3mks
2. A1V1= A2V2 OR volume flux is constant;
6= 0.02 x V
V = 300cm/s; 2mks
4.  Air is sucked into the venturi due to action of the engine pistons; Fast moving air into the venturi cause a decrease in pressure above the petrol pipe; Petrol is drawn into the venture due to this low pressure at the venturi and the high atmospheric pressure in the float chamber; Air and petrol mixture is thus drawn into the cylinders for combustion;
15.
1. Alcohol thermometer since it has a lower boiling point; 1mk
2.
1. Water rises up the tube; lmk
2. Air within the glass loses heat and contracts faster than glass; lowering the pressure within the flask below atmospheric value; 2mks
3. Heat ice and allow it to start melting. Insert the bulb into melting ice and mark the mercury level in the bore as x; Suspends the thermometer bulb in the space above water boiling under normal atmospheric pressure, and mark the new mercury level in the bore as y; use the grid to divide the distance xy into 100 equal parts. Each of the part is a degree; and this is your graduated thermometer.
Diagrams to be awarded lmark. 4mks
16.
1. The ratio of distance moved by EFart to distance mcvec  y Load at the same time; lmk
2.
1. Load = 20 x 10 = 200N
Work dare o- Load = F x d
=200 x 3 ;(formula or substitution)
2. Sin 32° = 3/L L =5.661m
Work done by the Effort = F x d
= 150 x 5.661; (sub)
= 849.2 J ; (ans) 2mks
3. Efficiency =  Work output x 100
Work input ;(either F or S)
= 600 x 100
849.2
=70.65% ;(ans) 2mks
ALTERNATIVELLY:   VR = 1/Sin 8   VR = 1/Sin 32 = 1.887
MA =L/E MA = 200/150 = 1.333
Efficiency = MA  X 100 = 1.333 x 100 ; (F or S)
VR               1.887
= 70.66% ; (ANS)
4. Wf = 849.2 — 600 = 249.2 J ; lmk
5. Ff W = F x d, 249.2 = Ff x d, Ff = 44N ; 1mk
17.
1. Heat capacity is the quantity of heat energy needed to raise the temperature of a substance by one kelvin while latent heat of fusion is the quantity of heat energy needed to convert a (given mass of a) substance from solid to liquid without change in temperature. 1mk
2.
1. to lower the pressure in the tube making the volatile liquid to vaporize ; 1mk
2. Ensures the volatile liquid circulates in the tubing; compresses the vapor to condensation; 2mks
3. Looses heat to the pipes through convection; 1mk
3. Heat lost by stear Q =mLv + mcAe
Q= 0.012 x L + 0.012x4200x (100-97);
= 0.012Lv + 151.2
Heat gained by water Q = 0.08x4200x74; =24864 J Heat gained = Heat lost;
0.0124+ 151.2 = 24864
Lv =2,059,400 J/kg ; 4mks
18.
1. Weighing balance reading increases; 2mks
2.
1. Upthrust =2.7 — 2.36 = 0:34N ;
Reading = 2.80 + 0.34 = 3.14N; 2mks
2. R.d =  Weight in air
Upthrust
= 2.70 = 7.941
0.34
Density = 1000 x 7.941 = 7941kg/m3; 2mks
2.
1. Wide bulb is to make the hydrometer float by displacing large volume of liquid. lmk
Lead shorts is to make hydrometer float vertically/upright; lmk
2. The hydrometer sinks less/floats more; 1mk
19.
1. Distance = Area under curve ;
Area → complete squares = 32
Incomplete squares = 15/2= 7.5
Total = 32 + 7.5 = 39.5 ;
Distance = 39.5 x (2x2.5) = 197.5m ; 3mks
(Allow for errors due to inconsistency of squares in the photocopies)
2. V1= 12.5, t1= 8
V2=25.0, t2=16
a =ΔV = 25.0 - 12.5 ; = 12.5 = 1.5625ms-2; 2mks
Δt           16-8             8
3. F = ma = 20 x 1.5625 ; = 31.25N ; 2mks
4. u=25m/s at P
x= ut, 22.5 = 25t,  t = 0.9s ;
s = ½ gt2
= ½  x 10 x 92;
= 4.05 metres ; 3mks