The figure below shows two parallel magnets with unlike poles adjacent to each other. Sketch the magnetic field pattern around the magnets (2mks)
Solution
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 State the conditions for generation of e.m.f from a magnet (2mks)
(a) The diagram in the figure below represents a wheel and axle used as a machine, whose efficiency is 80% to raise 400N of building materials. The wheel and axles have diameters of 75cm and 15cm respectively.
The diagram in the figure below represents a wheel and axle used as a machine, whose efficiency is 80% to raise 400N of building materials. The wheel and axles have diameters of 75cm and 15cm respectively.
(i) Mark on the diagram the correct position and direction of the load to be lifted (1mk)
(ii) Name the principle on which this machine works (1mk)
The principle of moments
(iii) Calculate the effort needed to raise the load (3mks)
(iv) The machine is operated manually and raises the load to a height of 5m in 20 seconds. Calculate the power developed by the operator (2mks)
(b)
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 Problem |  Solution |
The figure below shows a path taken by a gas molecule moving from point x to z
(a) Explain how this movement can be observed (1mk)
By strongly illuminating a suspension of pollen grains in water/dust particles in air or smoke cell
(b) State in full, the law of motion that governs movement from x to z (1mk)
A body continues in its state of rest or motion with uniform velocity unless acted upon by an external force
K.C.S.E Physics Q & A - MODEL 2019PP1QN17
​(a) State what ¡s meant by Brownian Motion.
(b) Figure 8 shows the graph of velocity against time For a small steel ball Falling in a viscous liquid.
(b) Figure 8 shows the graph of velocity against time For a small steel ball Falling in a viscous liquid.
​(i) Describe the motion of the steel ball as represented by part OA
(ii) Explain why the velocity of A and B is constant
(c)A student throws a tennis ball vertically upwards from the ground and it lands back after 8 seconds.( acceleration due to gravity g =10m/s2)
Determine the:
(i) maximum height reached by the ball
iii) velocity with which the ball hits the ground.
(ii) Explain why the velocity of A and B is constant
(c)A student throws a tennis ball vertically upwards from the ground and it lands back after 8 seconds.( acceleration due to gravity g =10m/s2)
Determine the:
(i) maximum height reached by the ball
iii) velocity with which the ball hits the ground.
answers
​(a) Continuous random motion of particles.
(b) (i) It accelerates, velocity increases.
(ii) As the ball falls through the fluid, the Viscous drag increases until the sum of the Viscous drag and the upthrust becomes equal the weight of the steel ball, hence the resultant force becomes zero.
(b) (i) It accelerates, velocity increases.
(ii) As the ball falls through the fluid, the Viscous drag increases until the sum of the Viscous drag and the upthrust becomes equal the weight of the steel ball, hence the resultant force becomes zero.
K.C.S.E Physics Q & A - MODEL 2019PP1QN14
​(a) A student is provided with five 20g masses, a meter rule, a spring with a pointer, a stand a boss and a clamp.
(i) In the space provided, sketch a labelled diagram of the set up that may be used in order to verify Hooke’s law using these apparatus.
(ii) State two measurements that should be recorded in order to plot a suitable graph so as to verify Hooke’s law.
(iii) Describe how the measurements made in (ii) can be used to determine the spring constant.
(i) In the space provided, sketch a labelled diagram of the set up that may be used in order to verify Hooke’s law using these apparatus.
(ii) State two measurements that should be recorded in order to plot a suitable graph so as to verify Hooke’s law.
(iii) Describe how the measurements made in (ii) can be used to determine the spring constant.
​(b) A helical spring stretches by 0.6cm when Supporting a weight of 40 g. Determine the extension when the same spring Supports a weight of 65 g.
answers
- (ii) Force due to total mass hung.
- Extension produced by hanging masses.
- (iii) — Plot a graph of force against extension.
- Determines the slope of the graph
​
K.C.S.E Physics Q & A - MODEL 2019PP1QN13
​ Two boxes E and F of masses 2.0 kg and 4.0 kg respectively arc dragged along a frictionless surface using identical forces. State with a reason which box moves with a higher velocity.
answer
- E (20N)
- F = Ma, the smaller the mass, the higher the acceleration
K.C.S.E Physics Q & A - MODEL 2019PP1QN12
Figure 5 shows two springs C and D of the same length and equal number of turns made from the same wire.
​State with a reason which of the two springs can support a heavier load before attaining the elastic limit.
answer
- C
- It has a smaller diameter hence a higher spring constant.
K.C.S.E Physics Q & A - MODEL 2019PP1QN11
A stone of volume 800 cm3 experiences an upthrust of 6.5N when fully immersed in a certain liquid. Determine the density of the liquid.
answer
K.C.S.E Physics Q & A - MODEL 2019PP1QN10
​For a fluid flowing at a velocity V in a tube of cross-sectional area A, VA =constant. State two assumptions made in deriving this equation.
answer
The assumptions are: the fluid is
- (i) flowing steadily,
- (ii) incompressible,
- (iii) non-Viscous.
K.C.S.E Physics Q & A - MODEL 2019PP1QN08
​Figure 4 shows a one meter long uniform rod of negligible weight supporting two weights.
​Determine the position of the fulcrum from 0 cm for the rod to remain in equilibrium.
answer
K.C.S.E Physics Q & A - MODEL 2019PP1QN07
A student carrying a heavy box using the right hand is observed to lean towards the left hand side. Explain this observation.
answer
- The box shifts the position of the center of gravity of the system towards the right hand to maintain equilibrium. The student leans in the opposite direction.
K.C.S.E Physics Q & A - MODEL 2019PP1QN05
​Figure 3 shows two metal rods A and B of equal length made of the same material but different diameters wax is attached at one end of each rod. A source of heat is placed between the two metal rods.
​State with a reason, what is observed on the wax.
answer
- Wax on rod B drops off first.
- The thicker rod conducts heat faster than the thinner one.
K.C.S.E Physics Q & A - MODEL 2019PP1QN04
​Figure 2 shows a round bottomed flask containing a coloured liquid. The flask is fitted with a capillary tube.
​It is observed that on holding the flask with bare hands, the level of the liquid in the capillary tube initially drops slightly and then rises. Explain this observation.
answer
- The flask absorbs heat from the hands and first expands hence level of liquid which expands more than the glass causing the rise.
K.C.S.E Physics Q & A - MODEL 2019PP1QN03
State two ways of reducing the surface tension of a liquid.
answer
- Using detergents/impurities
- Raising the temperature
K.C.S.E Physics Q & A - MODEL 2019PP1QN02
​Figure 1 shows a defective straw used to suck milk from a glass.
​It was observed that upon sucking the straw, milk did not rise up the straw. Explain this observation.
answer
- On sucking air rushes into the straw through the hole making it difficult to reduce pressure in the straw by sucking.
K.C.S.E Physics Q & A - MODEL 2019PP1QN01
A micrometer screw gauge has a -0.03 mm error. State the reading that is observed on the instrument when used to measure the diameter of a wire whose actual diameter is 0.38 mm.
answer
K.C.S.E Physics Q & A - MODEL 2019PP2QN18
(ii) Describe how a magnet can be demagnetised using the electrical method.
(b) You are provided with two iron bars P and Q. One of the bars is magnetized while the other is not. Explain how themagnetized bar can be identified without using a magnet or magnetic material.
(c)Figure 12 shows two identical copper coils X and Y placed close to each other. Coil X is connected to a DC power supply while coil Y is connected to a galvanometer.
(b) You are provided with two iron bars P and Q. One of the bars is magnetized while the other is not. Explain how themagnetized bar can be identified without using a magnet or magnetic material.
(c)Figure 12 shows two identical copper coils X and Y placed close to each other. Coil X is connected to a DC power supply while coil Y is connected to a galvanometer.
​Explain what is observed on the galvanometer When the Switch is closed.
(ii) State What is observed on the galvanometer when the switch is opened.
(iii) State what wou1d be observed if the number of turns in coil Y is doubled.
(ii) State What is observed on the galvanometer when the switch is opened.
(iii) State what wou1d be observed if the number of turns in coil Y is doubled.
answers
​(a) Place the bar magnet inside a solenoid placed in the an East-West direction then pass an alternating current through the solenoid
(b) Suspend each of the bars through its center of gravity and set it swinging in a horizontal plane shows a vertical axis through its centre
The magnetized bar will always come to rest in a north-south direction
(c) (i) The galvanometer pointer first deflects then moves back when the switch is closed a current builds up in a coil X and due to change influx linkage an emf is induced in coil Y making an induced current to flow through the galvanometer during the time current in coil X is rising. When current through coil X is steady no induced current flows through the galvanometer since there is no change in flux linkage
Therefore pointer deflects back
(ii) Pointer deflects in the opposite direction.
(iii) Magnitude of deflection increases
(b) Suspend each of the bars through its center of gravity and set it swinging in a horizontal plane shows a vertical axis through its centre
The magnetized bar will always come to rest in a north-south direction
(c) (i) The galvanometer pointer first deflects then moves back when the switch is closed a current builds up in a coil X and due to change influx linkage an emf is induced in coil Y making an induced current to flow through the galvanometer during the time current in coil X is rising. When current through coil X is steady no induced current flows through the galvanometer since there is no change in flux linkage
Therefore pointer deflects back
(ii) Pointer deflects in the opposite direction.
(iii) Magnitude of deflection increases
K.C.S.E Physics Q & A - MODEL 2019PP2QN13
State the disadvantage using a convex mirror as a driving mirror
answer
- Shows the object as being further than its actually is
K.C.S.E Physics Q & A - MODEL 2019PP2QN05
​In a siren, sound is produced when a jet of air is directed perpendicular to a ring of holes on a rotating wheel. Explain the effect on the pitch of sound produced when the speed of rotation of the wheel is increased.
answer
- Increasing speed increases the frequency of the sound causing an increase in the pitch(higher pitch)
K.C.S.E Physics Q & A - MODEL 2019PP2QN04
​Figure 2 shows an incomplete circuit for an electromagnet.
​(a) Complete the diagram to show how a battery should be connected at A so that the polarities at P and Q are South and North respectively.
(b) State two ways in which the strength of the electromagnet in (a) can be increased.
(b) State two ways in which the strength of the electromagnet in (a) can be increased.
answers
​(b) Increasing the number of turns in the coil
Increasing the current (or number of cells)
Increasing the current (or number of cells)
K.C.S.E Physics Q & A - MODEL 2019PP2QN03
State two properties of magnetic field lines around a bar magnet.
answers
- Do not cross one another
- They are complete loops
- Direction of field is from North to South
- They are normal to the surface at the poles
K.C.S.E Physics Q & A - MODEL 2019PP2QN01
Figure 1 shows two plane mirrors inclined at an angle of 120 to each other. A ray of light makes an angle of 40° with the first mirror.​
​By completing the ray diagram determine the angle of reflection on the second mirror.
answer
K.C.S.E Physics Q & A - MODEL 2018PP2QN07
​Figure 2 shows the image of an object O placed on the principle axis of a convex mirror.
​On the figure, draw a ray diagram to locate the object.
answer
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