Physics Questions and Answers - Form 2 End Term 1 Exams 2021

INSTRUCTIONS.

• Answer all questions in the spaces provided below.

1. Define the following terms giving appropriate examples. (4mks)
   1. Magnetic materials-
   2. Non-magnetic materials-
2. 0.01cm³ of oil spreads out on water to form a patch of diameter 28cm. estimate the diameter of an oil molecule ,and express your answer correct to 3s.f.g. (3mks)
3. A uniform meter rule with a mass of 200g suspended at zero mark is pivoted at the 22.0cm mark. Calculate the mass of the rule. (4mks)
4. State three uses of magnets. (3mks)
5. Explain the following. (4mks)
   1. Principal of moments of a force.
   2. Moment of a force is a vector quantity.
6. The micrometer screw gauge below has a zero error of -0.15.Determine the final Reading of the instrument. (3mks)
   
7. State two factors that affect the centre of gravity. Explain each briefly. (4mks)
8. State two practical applications of the C.O.G. (2mks)
9. A solid weighs 36N on the Moon .The force due to gravity on the moon is 1.7N/Kg. Determine the mass of the solid. (3mks)
10. Use simple sketches of a cone to illustrate the three states of Equilibrium. (3mks)
11.  
    1. Give a reason why water is not suitable as a barometric liquid. (2mks)
    2. Explain the application of 11(a) above. (1mk)
12. Determine the density in SI units of a solid whose mass is 40g measuring 30cm long, 4cm wide and 3cm thick. (4mks)
13.  
    1. Sketch two diagrams of a wire loop dipped in soap solution to illustrate the surface tension experiment. (2mks)
    2. Explain the observation in 14 (a) above. (2mks)
14. A uniform wooden bar of length 1m and mass 5kg is pivoted at 40cm mark as shown below. Calculate the value of F1. (4mks)
    
15. Using domain theory of magnetism, explain how a magnet may lose its magnetism on heating and hammering. (4mks)
16. Distinguish between soft and hard magnetic materials. (2mks)
17. A boy jumping from a high table tends to spread his legs. Explain (1mk)
18. State two differences between mass and weight. (2mks)
19. State two practical applications of friction. (2mks)
20. What is wrong with the statement.” the mass of an astronaut in the moon is ¹/₆th his mass on earth”. (1mk)
21. State the two conditions for a body to be in equilibrium. (2mks)
22. Explain what is meant by magnetic shielding and state one application of magnetic shielding. (2mks)
23. Define the following terms. (2mks)
    1. Principal focus-
    2. Radius of curvature-
24. An object is placed 30cm from a concave mirror of focal length 20cm. Calculate.
    1. The image position (2mks)
    2. The magnification (2mks)
25. State one advantage and one disadvantage of using a convex mirror. (2mks)

Marking Scheme

1.  
   1. materials that can gain magnetic qualities and act as magnets e.g iron
   2. materials that cannot be magnetized. e.g plastic
2. thickness =       volume       
                    area of the patch
   Area=πrxr=3.142 x 14 x 14=615.832cm²
   Volume=0.01cm³.
   t =   0.01   
        615.832     correct to 3s.f
3. weight of ruler at 0cm mark=2N, d=0.22m
   2Nx0.22=0.78 x w=0.56N=5.6kg
4.  
   • making compass direction
   • in radio speakers,tvs,etc any correct three.
5.  
   1. the sum of clockwise moments about a point = sum of anti-clockwise moments when the system is in equilibrium.
   2. has both magnitude and direction.
6. main reading=3.1mm
   thimble reading=0.26.
   total reading=3.36 − 0.15=3.21mm.
7.  
   • area of the base
   • position of C.O.G.
8.  
   • tripod stands
   • luggage buses
   • racing cars etc
9. F=mg
   m=^F/_g
   m=36N
        1.7N/kg
   =21kg.
10.  
      
11.  
    1. because of its anomalous expansion.
    2. Sea breeze, ice berg.
12. volume= 360cm³
    mass=40g.
    d=⁴⁰/₃₆₀=0.1111g/cm³x1000kg/m³=111.1kg/m³
13.  
    1.  
       
    2. dip this frame into a soap solution the tensive forces of the soap film quickly pull the slider AB to the far left end.
14. 0.2xF1= 0.6x100N=300N
15. A magnet is made up of numerous tiny magnets called domains inside it, all aligned parallel to one another. When a magnet is heated or hammered, the alignment is disturbed and they become randomly aligned. Thus there is no net magnetic effect.
16.  
    • soft=easily magnetized
    • hard=difficult to magnetise
17. maintain the C.O.G
18.  
    • mass=constant,kg, scalar.
    • Weight=varies.N, vector
19.  
    • movement of bodies.
    • Oiling.
20. mass is constant
21.  
    • The sum of forces on the body in one direction is equal to the sum of forces acting on the body in the opposite direction.
    • The sum of the clockwise moments about any point is equal to the sum of the anticlockwise moments about the same point.
22.  
    • Concentration of magnetic lines of force using soft iron rod and soft iron Ring.
    • Applications; used in electrical equipments and watches.
23.  
    1. principal focus: the point at which all rays parallel and close to the principle axis converge after reflection.
    2. Radius of curvature: the centre of the sphere of which the mirror is part.
24.  
    1. ¹/_f=¹/_v + ¹/_u,
       ¹/_v=¹/_f − ¹/_u,
       u=+30cm, f=+20cm, v=+60cm.
    2. m=^v/_u,
       m=⁶⁰/₃₀=2
25.  
    • Advantage: Used in supermarkets, driving.
    • Disadvantages: forms diminished images.