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A vibrator is sending out 8 ripples per second across a ripple water tank. The ripples are observed to be 4cm apart. Calculate the velocity of the ripples
Date posted:
September 6, 2019
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One of the factors that affect efficiency of a transformer is hysteresis losses. What is hyteresis losses?
Date posted:
September 6, 2019
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Give a reason why x-rays but not radio waves are used to detect fractured bones.
Date posted:
September 6, 2019
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The following figure shows the path of a ray of light through a transparent material placed in air.
Determine the refractive index of the transparent material
Date posted:
September 6, 2019
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The control grid in a cathode ray oscilloscope (CRO) is used to control the brightness of the beam on the screen. Explain how the brightness of the beam can be increased.
Date posted:
September 6, 2019
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A current of 0.7A flows through a wire when a potential difference of 0.35V is applied at the ends of the wire. If the wire is 0.5m long and has a cross-sectional area of 8.0 x 103mm2, determine its resistivity.
Date posted:
September 6, 2019
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The figure below shows a positively charged metal plate with an earthing connection. State and explain the final charge of the plate.
Date posted:
September 6, 2019
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The figure below shows a load of 50N being raised by pulling it along an inclined plane of length 2.0m.
Determine
i. The work done by the 22N force
ii. The work done against the load
iii. The efficiency of the system
Date posted:
September 6, 2019
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The figure below shows a buoy of capacity 40 litres and mass 10kg. It is held in position in sea water of
density 1.04g/cm3 by a light cable fixed to the bottom so that ¾ of its volume is below the water surface.
Determine the tension in the cable.
Date posted:
September 6, 2019
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The figure below shows a block with a graduated side and dimensions 4cm by 16cm, just about to be lowered
into a liquid in an overflow can.
During an experiment with this set-up, the following was recorded:
- The block floated with three-quarter of it submerged.
- Initial reading of balance = 0g
- Final reading of balance = 154g
Use the information to determine the density of
(i) the block
(ii) the liquid
Date posted:
September 6, 2019
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A bicycle wheel makes 300 revolutions per minute. Calculate the angular velocity of the wheel.
Date posted:
September 6, 2019
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The figure below shows two masses 0.1kg and 2kg connected by a string through a hole on a smooth horizontal surface.
The 0.1kg rotates in a horizontal circle of radius 3cm. Calculate the angular velocity of the 0.1kg mass, when the system is in equilibrium.
Date posted:
September 6, 2019
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Three insoluble powders A, B and C of densities dA, dB and dC, such that dA>dB>dC, are mixed and put into a container.The container is then whirled in a horizontal circle as shown in the figure below.
(i) Label on the figure, the positions of the powders after some time.
(ii) Give a reason for your answer in (i)
Date posted:
September 6, 2019
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A car decelerates uniformly from a velocity of 20m/s to rest in 4 seconds. It takes 4 seconds to reverse with uniform acceleration to its original starting point.
(i) Sketch a velocity time graph for the motion of the car.
(ii) Use your sketch in c (i) to determine the total displacement of the car.
Date posted:
September 6, 2019
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The figure below shows the displacement – time graph of the motion of a particle.
State the nature of the motion of the particle between?
(i) AB
(ii) BC
(iii CD
Date posted:
September 6, 2019
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State the physical quantity represented by the gradient of a displacement – time graph
Date posted:
September 6, 2019
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A substance of mass 2kg and specific heat capacity 400J/kg/k initially at 800C is immersed in water at 190C. If the final temperature of the mixture is 200C. Calculate the mass of water. (Specific heat capacity of water = 4200J/kg/k)
Date posted:
September 6, 2019
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A force of 20N is used to stretch a spring through 5cm. Calculate the elastic potential energy stored in the spring.
Date posted:
September 6, 2019
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A pipe of radius 3mm is connected to another pipe of radius 9mm. If water flows in the water pipe at a speed of 2m/s, what is the speed in the narrower pipe?
Date posted:
September 6, 2019
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A uniform 120m metal rod is pivoted near one of its ends and kept in equilibrium by a spring balance as shown in the figure below.
The reading indicated by the spring balance is 2.0N. Work out the mass of the metal rod. (g = 10N/kg)
Date posted:
September 6, 2019
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The spiral springs shown in the figure below are identical. Each spring has a constant K = 300N/m.
Determine the extension caused by the 150N weight (Ignore weight of springs and connecting rods)
Date posted:
September 6, 2019
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A micrometer screw gauge has a zero error of -0.02mm. It is used to measure the diameter of a wire. If the actual diameter of the wire is 0.28mm. Draw the micrometer screw gauge showing the diameter of the wire.
Date posted:
September 6, 2019
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A girl performed an experiment to measure the focal length of a converging mirror.In the experiment, a series of object distance,U(cm) and image distance V(cm) were obtained and the graph UV cm2 against V+U obtained as shown below.
Use the graph to determine:
i) Focal length of the mirror.
ii) Radius of curvature.
iii) State two applications of diverging mirror.
iv) Explain how a concave mirror is used by a dentist to enlarge image of the tooth.
Date posted:
August 22, 2019
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The figure below shows a standing wave formed when a string of length 1.5 m stretched between two supports is plucked in the middle.
(i) Explain how the standing wave is formed
(ii) Determine the wavelength of the standing wave
Date posted:
August 22, 2019
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The figure below shows crests of circular water waves spreading from two points A and B due to a vibrator. C and D are points on the surface of the water.
Given that the amplitude of each wave is 5 cm, state with a reason the amplitudes of the waves at point:
(i) C
(ii) D
Date posted:
August 22, 2019
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Sodium has a work function of 2.3eV. Given that: Planck’s constant h = 6.63 x 10-34JS, velocity of light in vacuum, C = 3.0 x108m/s, 1 electron-volt (1eV) = 1.6 x 10-19 C and mass of an electron, me = 9.1 x 10-31kg, calculate:
(i) Its threshold frequency.
(ii) The maximum velocity of the photoelectrons produced when the sodium is illuminated by light of wavelength 5.0 x 10-7m.
(iii) The stopping potential V, with the light of this wavelength.
Date posted:
August 22, 2019
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A G.M tube indicated a constant count rate of 5 counts per minute when a radioactive source was placed at a distance of about 10 cm from it. When the source was moved close to about 4cm the count rate varied as follows.
(i) The count rate was constant at a distance of 10 cm away. Explain
(ii) Plot a graph of count rate against time.
(iii) Use your graph to estimate the half-life of the radioactive source.
(iv) 
(v) State two precautions that have to be observed when using a radioactive substance.
(vi) Distinguish between fission and fusion.
Date posted:
August 22, 2019
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The figure below shows a circuit.
Calculate:
i) The total resistance of the circuit.
ii) The total current flowing in the circuit.
iii) The voltage drop across resistor R1.
iv) The current through the 3Ω resistor.
Date posted:
August 22, 2019
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The figure below shows a current carrying wire at right angle to a cardboard. Iron fillings are sprinkled on the card and card slightly tapped.
Draw and indicate the direction of the magnetic field pattern displayed on the card.
Date posted:
August 22, 2019
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Explain the behavior of the pins as illustrated below
Date posted:
August 22, 2019