**SECTION A (**25 marks**)**

**Answer all questions in this section in the spaces provided**

- In an experiment to measure the density of a liquid, a student filled a burette with a liquidto the 0 cm
^{3}mark. Figure 1 shows a section of the burette showing the level of the liquid after 54.5 g of the liquid had been run out.

Determine the density of the liquid ( 3 marks) - In an experiment to determine the acceleration due to gravity, g, a student measured the period, T, and length L, of a simple pendulum. For a length L = 70.5 cm, the period T obtained as 1.7s. Given that T = 2
**π**√^{L}/_{g}, determine the value of g correct to two significant figures. ( 2 marks) - A steel needle when placed carefully on water can be made to float. When a detergent is added to the water it sinks. Explain this observation.
- Figure 2 shows two cylinders containing a liquid and connected with a tight-fitting flexible tube. The cylinders are fitted with air- tight pistons A and B as shown.

When equal forces, F, are applied on the pistons as shown, it is observed that piston A moves up while B moves down. Explain this observation. (2 marks) - Two identical beakers A and B containing equal volumes of water are placed on a bench. The Water in A is cold while in B it is warm. Identical pieces of potassium permanganate are placed gently at the bottom of each beaker inside the water. It is observed that the spread of colour in B is faster than in A. Explain this observation. ( 2 marks)
- A clinical thermometer has a constriction in the bore just above the bulb. State the use of this constriction.

Use the following information to answer questions 7 and 8.

Two identical empty metal containers P and Q are placed over identical Bunsen burners and the burners lit. P is dull black while Q is shiny bright. After each container attains a temperature of 100^{0}C the burners are turned off. Identical test tubes containing water are suspended in each container without touching the sides as shown in Figure 3. - Explain why the container Q may become hot faster than P. ( 2 marks)
- Explain why the water in test- tube in P becomes hot faster than in Q. ( 2 marks)
- Figure 4 shows a uniform cardboard in the shape of parallelogram.

Figure 4

Locate the centre of gravity of the cardboard ( 1 mark) - The three springs shown in figure 5 are identical and have negligible weight. The extension produced on the system of springs is 20 cm.

Determine the constant of each spring ( 2 mks) - Figure 6 shows two inflated balloons hanging vertically on light threads.

Figure 6

When a stream of air is blown in the space between the balloons, they are observed to move towards each other. Explain this observations. ( 1 mark) - Figure 7 (a) shows the acceleration – time graph for a certain motion.

On the axes provided in figure 7 (b), sketch the displacement – time graph for the same motion. ( 1 mark) - State what is meant by
*absolute zero temperature*(zero Kelvin or -273^{0}C). (1 mark) - A turntable of radius 8 cm is rotating at 33 revolutions per second. Determine the linear speed of a point on the circumference of the turntable. (3 marks)
**SECTION B (55 MARKS)**Answer**all**the questions in this section in the spaces provided. - State
**two**factors that affect the boiling point of a liquid. ( 2 marks) - 100g of a liquid at a temperature of 10
^{0}C is poured into a well lagged calorimeter. An electric heater rated 50W is used to heat the liquid. The graph in figure 8 shows the variation of the temperature of the liquid with time.- From the graph, determine the boiling point of the liquid ( 1 mark)
- Determine the heat given out the by the heater between the times t= 0.5 minutes and t= 5.0 minutes ( 2 marks)
- From the graph determine the temperature change between the times t = 0.5 minutes and t= 5.0 minutes ( 1 mark)
- Hence determine the specific heat capacity of the liquid ( 2 marks)

- 1.8 g of vapour was collected from above the liquid between the times t= 6.8 minutes and t= 7.3 minutes. Determine the specific latent heat of vaporization of the liquid. ( 4 marks)

- State
- Define the term efficiency of a machine ( 1 mark)
- Figure 9 shows a drum of mass 90 kg being rolled up a plane inclined at 25
^{0 }to the horizontal. The force F applied is 420N and the distance moved by the drum along the plane is 5.2 m.

Determine:- The work done by the effort ( 3 marks)
- The work done in raising the drum ( 3 marks)
- The efficiency of the inclined plane as a machine ( 2 marks)

- State the law of flotation ( 1 mark)
- Figure 10 shows a rectangular metal block of density 10500 kgm
^{-3 }and dimensions 30 cm x 20 cm x 20 cm suspended inside a liquid of density 1200 kgm^{-3}by a string attached to a point 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 upthrust, U due to the liquid.- Write the expression relating T, W and U when the block is in equilibrium inside the liquid. ( 1 mark)
- Determine the weight, W of the block ( 3 marks)
- Determine the weight of the liquid displaced by the fully submerged block. ( 2 marks)
- Hence determine the tension, T in the string ( 1 mark)

- A certain solid of volume 50 cm
^{3 }displaces 10 cm^{3 }of kerosene (density 800 kgm^{-3}) when floating. Determine the density of the solid. ( 4 marks)

- State the pressure law for an ideal gas ( 1 mark)
- An air bubble is released at the bottom of a tall jar containing a liquid. The height of the liquid column is 80 cm. The volume of the bubble increases from 0.5 cm
^{3 }at the bottom of the liquid to 1.15 cm^{3 }at the top. Figure 11 shows the variations of pressure, P, on the bubble with the reciprocal of volume^{1}/_{v}, as it rises in the liquid.- State the reason why the volume increases as the bubble rises in the liquid Column ( 1 mark)
- From the graph, determine the pressure on the bubble:
- At the bottom of the liquid column; ( 2 marks)
- At the top of the liquid column ( 1 mark)

- Hence determine the density of the liquid in kgm
^{-3}( 3 marks) - What is the value of the atmospheric pressure of the surrounding? ( 1 mark)

- A rubber tube is inflated to pressure of 2.7 x 10
^{5}Pa and volume 3800 cm^{3 }at a temperature of 25^{0 }C. It is then taken to another place where the temperature is 15°C and the pressure 2.5 x 10^{5 }Pa. Determine the new volume. ( 4 marks)

- Define angular velocity ( 1 mark)
- Three masses are placed on a rotating table at distances 6 cm, 9 cm and 12 cm respectively from the centre of rotation. When the frequency of rotation is varied, it is noted that each mass slides off at a different frequency of rotation of the table. Table 1 shows the frequency at which each mass slides off.

Table 1- State
**two**factors that determine the frequency at which each mass slides off. ( 2 marks) - Oil is now poured on the table before placing the masses. Explain the effect of this on the frequency at which each mass slides off. ( 2 marks)

- State
- Figure 12 shows a flywheel of radius 14 cm suspended about a horizontal axis through its centre so that it can rotate freely about the axis. A thread is wrapped round the wheel and a mass attached to its loose end so as to hang at a point 1.26m above the ground.

When the mass is released, it accelerates at 0.28 ms^{-2}. Determine the angular velocity of the wheel just before the mass strikes the ground.( 4 marks)

- Define angular velocity ( 1 mark)

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