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The diagram figure below shows an electromagnet made by a student of Nyamogo Girls
secondary school, in the laboratory. The magnet was meant to pick up and release a metal object
(i) Name giving reasons a suitable material for part X
(ii) The electromagnet will just lift a metal of mass 150g. Taking g = 10N/Kg, what will be the
least force exerted by the magnet to do this
(iii) State the changes which the student should make so that a heavier metal object could be
lifted by the magnet
(iv) Explain why the strength of the above magnet cannot be increased indefinitely
Date posted:
April 4, 2019
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Draw the magnetic field pattern around the magnets below.
Date posted:
April 4, 2019
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Two pins are attached to each of the magnets as shown below.
Explain the behaviour of pins in each case.
Date posted:
April 4, 2019
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The figure below shows a micrometer screw gauge being used to measure the diameter of a rod.
The thimble scale has 50 divisions.
What is the reading?
Date posted:
April 4, 2019
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A gold leaf electroscope is positively charged as shown in the diagram in figure where C is the cap and L is the gold leaf. State and explain what happens to L when a positively charged rod is
brought near C without touching it.
Date posted:
April 4, 2019
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In the figure below, explain what happens when one of the metal balls comes into contact with
a negatively charged rod.
Date posted:
April 4, 2019
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Two identical spheres A and B each standing on an insulated base are in contact. A
negatively charged rod is brought near sphere A as shown below
In what way will A differ from B if separated while the rod is near?
Date posted:
April 4, 2019
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Two metal cons A and B of different sizes rest on two identical gold leaf electroscope as shown.
Compare the divergence of the gold leaves of the two electroscopes. Explain your answer
Date posted:
April 4, 2019
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The figure below shows an uncharged pith ball under the attraction of a charged ball.
State and explain what would be observed after the two pith balls touch
Date posted:
April 4, 2019
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The length of a pinhole camera is 20cm. Determine the height of a storey building 300m away
from the pin hole if the image formed on the screen of the pin hole camera is 2.5cm high
Date posted:
April 4, 2019
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Explain why transformers are widely used throughout the national grid system
Date posted:
April 4, 2019
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A coil of wire is connected in series with a battery, a rheostat and a switch as shown in figure
(i) Draw on the diagram, the shape of the magnetic field inside and outside the coil when the
switch is closed.
If the jockey J on the rheostat is moved towards Q what’s the effect on:-
(ii)The resistance of the circuit
(iii) The current through the coil
(iv) The magnetic field in the coil
Date posted:
April 4, 2019
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A student hung a magnet next to a coil of wire to make a door chime as shown in figure :-
i) Explain how the current made the magnet move towards the chime bar
(ii) What should the student do to make the magnet hit the chime bar harder?
Date posted:
April 4, 2019
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The current capacity of an accumulator is 40Ah. Find the amount of current flowing if the
accumulator is used for 600 minutes
Date posted:
April 4, 2019
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In the diagram below, the U-tube contains two liquids; X and Y which do not mix. If the density
of liquid Y is 900Kgm-3 and that of X is 1200Kgm-3, calculate the height of liquid Y
Date posted:
April 4, 2019
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The figure below shows two mini buses A and B at a speed of 40m/s and 20m/s
respectively moving in opposite directions. They collided head on
Determine the common speed of the vehicles if they stuck to each other
Date posted:
April 4, 2019
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A footballer kicks a ball of 600g initially at rest using a force of 900N. If the foot was in
contact with the ball for 0.1sec. What was the take off speed of the ball?
Date posted:
April 4, 2019
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State the law of inertia
Date posted:
April 4, 2019
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A minibus of mass 2000kg traveling at a constant velocity of 36km/h collides with a stationary
car of mass 1000kg. The impact takes 2 seconds before the two move together at a constant
velocity for 20 seconds. Calculate:
(i) The common velocity
(ii) The distance moved after impact
(iii) The impulse force
(iv) The change in kinetic energy
Date posted:
April 4, 2019
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(i) complete the diagram below to show how the pulley can be used to raise a load L by
applying an effort E
(ii) The pulley system above has a mechanical advantage of 3. Calculate the total work done
when a load of 60N is raised through a height of 9M
Date posted:
April 4, 2019
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A hydraulic machine is used to raise a load of 100kg at a constant velocity through a height
of 2.5m. The radius of the effort piston is 1.4cm while that of the load piston is 7.0cm. Given
that the machine is 80% efficient, calculate:-
(i) The effort needed
(ii) The energy wasted in using the machine
Date posted:
April 4, 2019
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Name one machine that has a velocity ratio of less than one (V.R < 1)
Date posted:
April 4, 2019
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The figure below shows a pulley system being used to raise a load.
If a load of 100N is raised by applying an effort of 48N, determine the efficiency of
the system.
Date posted:
April 4, 2019
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Vicky performed an experiment using a pulley system as shown in the figure.
(a) What is the V.R. of the system?
(b) Determine the M.A. of the system. *
(c) Calculate the efficiency of the system.
(d) Explain why efficiency of a practical machine is always less than 100%
(e) If the load moves a distance of 5 cm. Find the work done on the load.
Date posted:
April 4, 2019
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An inclined plane of length 5m is used to raise a body of mass 60kg to the back of a lorry. If the
plane is inclined at an angle 25° from the horizontal, calculate the efficiency of the system given
that a constant force of 650 N is used to push the body up the plane
Date posted:
April 4, 2019
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Sketch a velocity-time graph for a body moving with zero acceleration
Date posted:
April 4, 2019
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State the three equations of linear motion.
Date posted:
April 4, 2019
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A car is traveling uniformly at 100km/hr when the driver observes a road block ahead.
He takes 0.5 s before applying the brakes which brings the car to rest with a uniform
deceleration of 4m/s2. Determine the distance traveled by the car from the time the driver
observed the road block until the car comes to rest.
Date posted:
April 4, 2019
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In an experiment on momentum, trolley P of mass 800g was attached to a ticker timer of
frequency 50Hz. Trolley P, initially moving with a velocity of 0.5m/s, was made to collide
with a stationary trolley Q of mass 400g. A copy of the tape as it appeared after the collision is
presented in the figure below:-
a) Determine the velocity of the trolley P after collision
(b) Calculate the impulsive force experienced by trolley P
Date posted:
April 4, 2019
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A ball of mass 100g is kicked horizontally from the top of a cliff. If the ball takes 4 seconds
to hit the ground, determine the height of the cliff
Date posted:
April 4, 2019