PHYSICS-1 FORM FOUR MOCK EXAMINATION 2021 BUSEGA DISTRICT

THE UNITED REPUBLIC OF TANZANIA

PRESIDENT’S OFFICE – REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT

BUSEGA DISTRICT COUNCIL

FORM FOUR DISTRICTMOCK EXAMINATION

Code 031/1 PHYSICS-1

TIME: 3 Hours.                          FRIDAY, 28^thMAY, 2021 A.M.

Instructions

1. This paper consists of section A, B and C.
   
2. Answer all questions in section A and B,and anyTwo(2)questions from section C.
   
3. Non programmable Calculators are allowed and cellular phones are not allowed in the examination room.
   
4. Write Examination number on every page of your answer sheet(s).
   
5. Where necessary the following constants may be used:
   
   1. Acceleration due to gravity, g = 10m/s²
      
   2. Density of water = 1g/cm³ or 1000kg/m³
      
   3. Density of gold = 19.3g/cm³
      
   4. Density of silver = 10.5g/cm³
      

   SECTION A: (15 Marks)
   

   Answer all questions from this section
   

    

6. For each of the items (i)-(x), choose the correct answer from among the given alternatives and write its letter beside the item number in the answer sheet(s) provided.
   
   1. The SI unit of moment is;
      
      1. Ns
         
      2. Kgm/s
         
      3. JS
         
      4. Nm
         
   2. Potential and kinetic energy are similar in that
      
      1. Both produce heat
         
      2. Both are measured in watts
         
      3. One is substitute of the other
         
      4. Both are forms of mechanical energy
         
   3. The difference between scalar and vector quantity is that:
      
      1. A vector has magnitude only
         
      2. A Scalar has magnitude and direction
         
      3. A vector has magnitude and direction while the scalar has magnitude only
         
      4. All of the above mentioned are correct answers.
         
   4. A spectrum is formed when the image of the slit do not overlap is called;
      
      1. Impure spectrum
         
      2. Pure spectrum
         
      3. Invisible spectrum
         
      4. Color mixing
         
   5. A can of mass 600kg accelerates from rest to 8m/s in 40 second. The resultant force acting on the car is
      
      1. 60N
         
      2. 120N
         
      3. 160N
         
      4. 70N
         
   6. The pressure of water in a dam is greater at the bottom which of the following is a reason as to why a dam has thick walls at bottom?
      
      1. To counter-balance the pressure
         
      2. To accommodate more water
         
      3. To reduce energy generation
         
      4. None of the above
         
   7. The use of vessels like aeroplanes, ships and cars is the application of physics in
      
      1. Communication
         
      2. Industry
         
      3. Entertainment
         
      4. Transport
         
   8. The process of forming hydrogen bubbles around the copper plates of a cell is
      
      1. Hydrogenation
         
      2. Local action
         
      3. Amalgamation
         
      4. Polarization
         

1. Pond skaters and mosquitoes are able to walk on surface of water because of the
   
   1. Density of water
      
   2. Upthrust of water
      
   3. Capillarity
      
   4. Surface tension
      
2. The shaving mirror is a typical application of a
   
   1. Concave mirror
      
   2. Convex mirror
      
   3. Plane mirror
      
   4. Rotating mirror
      

       

1. Match the items in List A with the responses in List B by writing the letter of the correct response beside the item number in the answer sheet(s) provided.
   

    

   LIST A	LIST B
   Occur in a circuit as result of changing current in the nearly circuit Applies when motion in conductor under magnetic field causes current Parallel current in the same direction Parallel currents in opposite directions Applies when current carrying conductor in a magnetic field cause motion.	Repulsive force Dynamo rule Eddy current Attractive force Mutual induction Motor rule Self-induction Lenz’s law Faradays law Magnetic field.

    

SECTION B: (60 Marks).

Answer all questions from this section

1. A small object was kicked vertically upwards from the ground with initial velocity of 40m/s
   

   (a) Sketch the displacement-time graph for the whole motion of the object until it reaches the ground. (4marks)
   

   (b) How high did the object moved? And how long will it take for the body to be in air?(6marks)
   

2. (a). (i) Define Pressure and State its SI unit(1 mark)
   

   (ii) State Pascal’s principle(1mark)
   

   (iii) Use figure 1 below to calculate the pressure of steam in the cylinder which would just raise the valve if the area of the valve in contact with the steam is 5cm². Atmospheric pressure is 10⁵N/m².
   

           20cm 30cm
   

       Pivot
   

    F

Steam     Figure 1. (3 marks)

(b). A uniform tube 96cm long sealed at end, is lowered vertically with its open end downwards into mercury until the length of the enclosed air column is 84cm. with the aid of a diagram, find the depth of immersion of the tube in the mercury if the atmospheric pressure is 77cm of mercury. (5marks)

1. (a) (i) Explain why it is not advisable for soldiers to march across the bridge in rhythm. (2 mark)
   
   1. The frequency obtained from a plucked string when the tension is 2N is 400HZ. Calculate the frequency when the tension is increased by 6N.(4 marks)
      

(b)The diagram below shows the electromagnetic spectrum. Region D represents visible light

Increasing frequency.

        Figure 2.

Which region represents radiations

1. Capable of promoting the production of vitamin D in the skin?
   
2. Used in radar system? (4 marks)
   
3. Produced in nuclear reactors?
   
4. Used for diagnosis of denser tissue like bones and in treatment of cancer in the hospital.
   

    

1. (a) Explain why do two identical cells in series drive more current through the resistor than one does, and why do they not double the current?(5marks)
   

   (b) A steel tape of correct length at 20 is used to measure a distance on a day when a temperature is 30. If the linear expansivity of steel is 0.000011/K, what is the error in measuring a distance of 20m?(5marks)
   

    

2. (a) (i) Could a camera with a concave lens instead of a convex lens still take Picture? Explain. (1 mark)
   

(ii) Use a diagram to explain why short-sighted people cannot see distant objects clearly.(2 marks)

(iii) Explain using a diagram, how the inserting a suitable lens in front of the eye will correct its defect.(2marks)

(b)(i) Why does air cool when it rises through the atmosphere?(2marks)

(ii) State three (3) differences between absolute humidity and relative humidity (3marks)

1. (a) A crown made of gold and silver has a volume of 60 cm³ and a mass of 1.05 kg. find the mass of gold contained in the crown (4 marks)
   

   (b).A body of mass 40kg is placed in a straight track sloping at an angle of to the horizontal. If the body is held from slipping by friction, calculate the normal reaction and the force of friction.(6marks)
   

SECTION C (25 marks)

Answer only two(2) questions from this section

9. (a)(i) State the Maxwell’s Right hand screw Rule.(2 marks)

(ii) Using the Maxwell’s Right hand screw Rule, show the direction of the field on two parallel current carrying conductors in the same direction. Show the direction of force.(4marks)

(b)A transformer is designed to work from 240V a.c mains to give a supply at 8V to ring house bells. The primary coil has 4800 turns.

(i) How many turns would you expect a secondarycoil to have? (2 marks)

(ii).State how the voltage so required is reduced or increased? (1 mark)

(iii).How is the efficiency of this transformer made as higher as possible? (1 mark)

(iv) Explain why the primary current decreases when a bell is being rung. (1 mark)

(v).What would happen if the transformer were connected to 240V d.c mains? (1.5 mark)

10. (a) Briefly explain the differences between conductors, semiconductors and insulators in terms of energy level(6.5marks)

(b). State any six(6) differences between stars and planets (6marks)

11. (a). Explain the nature of penetration of rays and explain how each can be prevented from penetrating through others substances(6.5marks)

(b).i. Explain why cathode ray tubes (CRT) are evacuated?(2marks)

ii.What happens to the CRTwhen a gas is maintained?(2marks)

iii. If a gas is maintained in a CRT, will the image be formed onto the screen? Explain. (2marks)