1. a)  Describe the principle operation of an ideal transformer. [3]
  2.  
  1. Give an expression for the flux linking the coil when the normal to plane of the coil is at an angle directly proportional to the direction of B.
  2. If at a time t=o the normal to the plane of the coil is in the same direction as that of B, show that emf ,E induced in the coil is given by E=BAwsinwt.
  3. With the aid of a diagram, describe the position of the coil relative to B when E is 1)maximum

    •  

Explain your answer[6]

               c) Explain why oil is used in transformers                               [3]

 

 

2.    a) Explain how an object can undergo acceleration at a constant speed . [2]

       b) An object of mass 0.5 kg is rotated in a horizontal circle by a string 1 meter long . The maximum tension in the string before it breaks is 50 Newtons. What is the greatest number of revolutions per second of the object.[4]

     c) Explain, with the aid of a clear diagram , why

  1. A cosmonaut in a satellite which is in a free circular orbit around the earth experiences the sensation of weightlessness even though he is influenced by the gravitational field of the earth.
  2. Cars travel at high speeds on banked roads than a horizontal bend.        [4]

 

 

3.  a) State Newton’s second and third laws of motion [2]

      b) A constant force of 9.5 N acts on a sphere on a mass 230g lying on a smooth horizontal surface as shown below.

                                                            A

                                                          

 

 

  1. The sphere A from rest and after 5.00 seconds the force is removed . Sphere A collides elastically with sphere B of mass 250g initially at rest.
  1. Force exerted on the sphere A by the surface.
  2. The change of momentum of sphere A before collision.
  3. The velocity of sphere A, just before collision
  4. Deduce the velocity of sphere A , after the collision
  1. Explain why boxers use gloves when fighting                                                      [8]

4. a)State Ohm’s Law                                                                                                             [2]

    b)Sketch and explain the I-V characteristic graph of a semiconductor diode and filament   lamp[6]

   c) Fig 3.2 Shows a fuel tank gauge

The ammeter is calibrated to read ‘full tank’ at maximum deflection . Explain how the gauge in fig 3.2 works                                        [4]

5 a) Explain the following terms

  1. Phase difference
  2. Polarised light                                                                                                    [3]

b) A girl notices that a boat moored behind a sea wall is bobbling vertically up and and down due to the action of the waves.

She sees that the lamp at the top of the mast is visible above the wall for a total time of one second and is hidden for a total time of 3.0 seconds. The maximum height of the lamp above the wall is 0.3 metres.

Assuming that its in Simple Harmonic Motion ,calculate

  1. Amplitude of the motion of the boat
  2. Speed of the as it disappears behind the wall

Given that the girl and the boat are 18 metres apart and the wavelength =3.6 m . Calculate the phase difference .

Show the girl and the boat on the wave                                                [6]

c) Explain the conditions required if two-source interference fringes are to be observed . [3]

 

 

 

 

Hartzell

6. a)   State the kinetic theory of gases

           Briefly explain what is meant by the term ideal gas.

 

 b) Mitrogen gas under an initial pressure of 5×10⁶ Pa at 15°C is contained in a cylinder of volume 0.040 m³. After a period of 3 years has fallen to 2×10⁶ Pa at the same tempreture because of leakage

[Assume molar mass of nitrogen = 0.028 kgmolꜗ, R= 8.31 JmolꜗKꜗ, Avogadro Constant = 6×10˄23 molꜗ]

Calculate

  1. The mass of nitrogen originally present in the cylinder
  2. The mass of gas which escaped from the cylinder in three years
  3. The average number of nitrogen molecules which escaped from the cylinder per second.

[Take one year to be equal to 3.2×10⁷ seconds ]

c) Why is the energy needed to raise the temperature of a given mass of gas by a certain amount is greater if the pressure kept constant than if the volume is kept constant.

7 . A ball B of mass 1.2kgs travelling at constant velocity collides head on with a stationery ball S of mass 3.6kgs as shown below

Frictional forces are negligible.

The variation with time (t) of the velocity (v) of the ball (B), before , during and after colliding with ball S is shown below.

The significance of positive and negative values of v in the above graph.

  1. Use the graph to determine, for ball B during the collision with S ,
  1. The change in momentum of the ball B
  2. The magnitude of the force acting on B
  1. Calculate the speed of ball S after collision.
  2. Using answers above deduce quantitatively whether the collision is elastic or inelastic.
  3. A neutron moving with velocity 3.96 × 10⁷ msꜗ collides head on elastically with a helium atom moving with velocity of 2.97× 10⁷ msꜗ in the opposite direction. Calculate the velocity of the neutron and the helium atom after collision.

[ He = 6.64×10˄-27 kg  ; electron =1.66×10˄-27 ]   

 

 

Bonda Girls High

8. a)

  1. State and explain the difference between stationery and progressive waves .     [2]
  2. A progressive and a stationery simple harmonic wave each wave the same frequency of 250 Hz and the same velocity of 30msꜗ. Calculate
  1. The phase difference between two vibrating points on the progressive wave which are 10 cm apart.
  2. The difference between nodes in the stationery wave. [3]

 

 

b)

A steel ball A of mass 4kgs supported on alight cord of 3m long is held at a sixty degrees angle from the vertical as shown above. A second steel ball B of mass 1kg rests just at the edge of the table which is 1.5 m high. B all A is released and strikes ball B head-on in a perfectly elastic collision.

  1. Approximately how long after A is released does B strike the floor?
  2. How fast is A moving when it strikes B ?
  3. How far out from the base of the table does B strike?            [6]

c) Sketch a graph showing a V-X relationship of a particle undergoing simple harmonic motion. [1]

9. a)  Explain with aid of a diagram why airflow over the wings of an aircraft causes a lift.

   b) One mole of a gas is confined in a cubical container of side A. The number per unit volume of the molecules is u, and the mass of each molecule is m. In a simple model , the system may be assumed to behave as if at any instant one-sixth of the molecules in the container are moving with speed c directly  towards each of the faces of the cube. Show that the number of molecules hitting a cube face per unit time is ⅙ na 2c and hence show that the pressure, p , of the gas is given by P=⅓nmc2

c) A container holds a mixture of hydrogen and oxygen in thermal equilibrium at a temperature at 500K. Find the mean translational kinetic energies of both types of molecule. Given that the mass of a hydrogen molecule is 3.34 ×10˄-27 kg and the oxygen molecule is 16 times more massive, find the r.m.s. speeds of both types of molecule.

  

10. a) Explain what is meant by

  1. The equilibrium
  2. The stability of a body.

b) Explain  why a lift force can be when an object with an aerofoil shape , such as a wing travels through air.

A helicopter, travelling forward with constant velocity, is shown below

 

 

 
 

 

 

 

 

 

 

 

  1. Why must the helicopter have its rotor angle horizontal.
  2. Draw a force diagram showing the  lift L provided by the main rotor , the weight w of the helicopter and the total drag force on the helicopter
  3. What is the resultant of these three forces

 

Sketch diagrams showing the altitude of the helicopter ( i.e. its position relative to the horizontal)

  1. As it slows down
  2. When it hovers

c) The mass of the helicopter is 6000kg and the main rotor moves 200kg of air vertically downwards each second . Starting from Newton’s second law calculate the average downward velocity of this air if the helicopter is hovering.

d) Use Stoke’s law to explain how a body falling through a viscous fluid under laminar conditions attains terminal velocity