Figure 6 shows an athlete lifting weights while standing with the feet apart.
Explain why standing with the feet apart improves the athlete’s stability.(Answered) State the principle of moments.(Answered) Giving a reason, name the state of equilibrium of the toy.(Answered) Figure 3 shows a bimetallic strip with a wooden handle, suspended horizontally
using a thin thread.
The strip is heated at the point shown. Explain why the system tips to the right.(Answered) Figure 3 shows a rectangular block of wood with a hollow section (inside) at the
position shown. The block is resting on a horizontal bench
(i) State the effect on the stability of the block when the hollow section is filled with water.
(ii) Explain your answer in (i) above.(Answered) Figure 3 shows two identical trolleys with loads A and B.the loads are identical in
shape and size. Given that the density of A is greater than that of B,
explain why the trolley in figure 3(ii) is more stable.(Answered) If the portion of the rock represented by the shaded part is chopped off, explain
why the rock may topple to the right.(Answered) Figure 3 shows two identical hollow spheres. Sphere A is completely filled with the
liquid while B is partially filled with identical liquid. When the two spheres are
rolled gently on a horizontal surface, it is observed that the sphere B stops earlier
than the sphere A. Explain this observation.(Answered) Figure 2 shows a beaker placed on a bench. A block of ice is placed in the beaker
as shown.
State and explain the change in the stability of the beaker when the ice melts.(Answered) State how the position of the centre of gravity of a body in stable equilibrium
changes to that in the rest position when the body is slightly tilted and then
released.(Answered) State two factors that should be controlled in manufacturing a cylindrical
container of uniform thickness, which should normally be in a standing position.(Answered) What is meant by the centre of gravity of a body?(Answered) Figure 3 shows two metal rods A and B of equal length made of 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 reason, what is observed on the wax.(Answered) State two ways in which mercury based thermometer can be modified to read very small temperature changes.(Answered) Explain how a greenhouse gets warm.(Answered) Figure 6 shows a glass tube with water fitted with two identical thermometers A and B. it is heated as shown.
State with reason which one of the two thermometers shows a higher temperature.(Answered) Figure 4 shows a source of heat placed at equal distances from two identical flasks X and Y containing air. The surface of X is painted black while Y is clear.
X and Y are linked by a U-tube filled with water whose level S and T are initially the same; it is later observed that S falls while T rises. Explain this observation.(Answered) Figure 3 shows a piece of wood fitted into a copper pipe and a piece of paper wrapped tightly around the junction.
It is observed that when a flame is applied around a paper at the junction, the
side of the paper around the wood burns first. Explain this observation.(Answered) (a) Figure 11 shows how underground room was ventilated. It had two vents, one at A and the other at B. A fire was lit at point C. Explain what happened to the ventilation when fire was lit.
(b) Explain how a vacuum flask minimizes loss of heat through radiation.(Answered) Figure 4 shows identical beakers P and Q full of water at #90^0C#. Two similar cold wet clothes are wrapped, one around the top of P and the other around the bottom Q.
State with a reason the beaker in which the water cools faster.(Answered) A paper windmill in a horizontal axis was placed above a candle as shown in figure 2. When the candle was lit the paper windmill begun to rotate. Explain this observation.(Answered) Two identical empty metal containers P and Q are placed over identical Bunsen burners and the burners lit. P is dull black while Q is shiny bright. After each container attains a temperature of #100^0C# the burners are turned off. Two identical test tubes containing water are suspended in each container without touching the sides as shown in figure 3.
(Answered) Two identical empty metal containers P and Q are placed over identical Bunsen burners and the burners lit. P is dull black while Q is shiny bright. After each container attains a temperature of #100^0C# the burners are turned off. Two identical test tubes containing water are suspended in each container
without touching the sides as shown in figure 3.
Explain why container Q may become hot faster (Answered) Figure 3 shows a hot water bath with metal rods inserted through one of its sides. Some wax is fixed at the end of each rod.
Besides the length of the rods that is kept constant, what else should be kept constant when comparing the property for the different metal rods?(Answered) Figure 3 shows a hot water bath with metal rods inserted through one of its sides. Some wax is fixed at the end of each rod.
What property of metals could be tested using this set up.(Answered) Figure 4 shows two identical balloons A and B. The balloons were filled with equal amounts of the same type of gas. The balloons are suspended at a distances x1 and x2 from a metal cube filled with boiling water and placed on an insulating material.
State the mode by which heat travels from the cube to the balloons.(Answered) In a vacuum flask the walls enclosing the vacuum are silvered on the inside. State the reason for this.(Answered) Two identical aluminium rods are shown in figure 4. One rests on metal block and other on a wooden block. The protruding ends are heated on a Bunsen burner as shown.
State with reason which bar the wax likely to melt sooner.(Answered) When a Bunsen burner is lit below wire gauze, it is noted that the flame initially burns below the gauze as shown in figure 5(i). After some time, the flame burns below as well as above the gauze as shown in figure 5(ii)
Explain the observation.(Answered) An electric heater is placed at equal distances from two similar metal cans A and B filled with water at room temperature. The outer surface of can A is shiny while that of B is dull black. State with reasons which can will be at a higher temperature after the heater is switched on for some time.(Answered) Figure 1 below shows a cross –section of a vacuum flask.
(i) Name the parts labeled A and B
(ii) Explain how the heat losses are minimized when hot liquid is poured into the flask.
(iii) Boiling water is poured into two identical vacuum flasks A and B. flask A is partially filled while B is completely filled. Both
are closed tightly. State with reasons the flask in which the water is likely to hav(Answered) Figure 12 shows two identical containers A and B into which a copper rod is fitted. The containers are well lagged.
The liquids in the containers were initially at the same temperature. If the heat is applied continuously at the position shown, state with a reason the container through which the loss of heat is likely to be higher.(Answered) A wooden bench and a metal bench are both left in the sun for a long time. Explain why the metal bench feels hotter to touch.(Answered) In fig 4 one end of a metal rod is placed in steam and the other end in melting ice. The length of the rod in between is lagged.
State two factors that determine the rate at which ice melts.(Answered) Give a reason why heat transfer by radiation is faster than heat transfer by conduction.(Answered) State two variables that must be controlled in an experiment for comparing the thermal conductivities of different metal rods of the same diameter(Answered) In the set up shown in figure 3, water near the top of the boiling tube boils while at the bottom it remains cold
Give a reason for the observation.(Answered) Figure 6 shows two solids W and X made of the same material and immersed in water.
(i) State with a reason one of the containers experiences a greater upthrust.(Answered) A balloon is filled with a gas which is lighter than air. It is observed to rise in air up to a certain height. State a reason why the balloon stops rising.(Answered) A ship made of steel is observed to float on water yet the density of steel is approximately eight times that of water. Explain this observation.(Answered) State the condition necessary for a body to float in a fluid(Answered) The system in figure 8 is in equilibrium
When the temperature of the water is raised the system is observed to tilt to the right. State the reason for this observation.(Answered) The system in figure 8 is in equilibrium When the temperature of the water is raised the system is observed to tilt to the right. State the reason for this observation.(Answered) Figure 14 shows a cork floating on water and held to the bottom of the beaker by a thin thread.
(i) Name the forces acting on the cork
(ii) Describe how each of the forces mentioned in (i) above changes when water added into the beaker until it fills up.(Answered) Figure 13 shows a simple hydrometer
(i) State the purpose of the lead shots in the glass bulb
(ii) How would the hydrometer be made more sensitive?
iii) Describe how the hydrometer is calibrated to measure relative density.
(Answered) State the law of floatation(Answered) State Archimedes principle(Answered) The uniform bar in Figure 7 is pivoted at its midpoint. It is in equilibrium under the action of two identical balloons filled with equal volumes of different light gases at the same temperature.
Explain why the bar may not remain in equilibrium if the temperature of the surrounding changes.(Answered) The system in Figure 2 is in equilibrium at room temperature.
The system is taken outside where the temperature is 100c higher for some time.
Explain why this tips to the right immediately it is returned to the room.(Answered) When a piece of metal is placed on water, it sinks. But when the same piece of metal is placed on a block of wood, both are found to float. Explain this observation.(Answered) Figure 2 shows a uniform bar in equilibrium.
When water is added into the beakers A and B until the weights are submerged, it is observed that the bar
tips towards B. Explain the observation.(Answered) (i) You are provided with the following :
-an overflow can
-a spring balance
-water
-a beaker
-a metal block
-a string
Describe an experiment to verify Archimedes principle(Answered) Explain the following observation: ice cubes float on water and solid benzene sinks in liquid benzene(Answered) A solid copper sphere will sink in water while a hollow copper sphere of the same mass may float. Explain this observation(Answered) The wavelength of a radio wave is 1km. Determine its frequency. (Take the speed of light as #3.0 times 10^8 ms^-1#)(Answered) Figure 2 shows how the displacement varies with time for a certain wave.
Determine the frequency of the wave.(Answered) Figure 4 shows a hack- saw blade clamped horizontally on a bench and the free end is made to vibrate about the rest position.
The movement 0→a→0→b→0→a→0→b,
takes 0.7 seconds. Determine the frequency of the vibration of the blade(Answered) Figure 10 represents a transverse wave of frequency 5 Hz travelling in the x direction.
Determine the speed of the wave.(Answered) Figure 5 shows the displacement time graph of a wave travelling at 200cm/s.
Determine for the wave, the
(i) Amplitude
(ii) Period
(iii) Frequency
(iv) Wavelength(Answered) State one difference between mechanical and electromagnetic waves.(Answered) The audible frequency range for a certain person is 30Hz and 16500 Hz. Determine the largest wavelength of sound in air the person can detect.
(speed of sound in air=330m/s)(Answered) Give one example of a longitudinal wave.(Answered) Figure 2 represents a displacement-time graph for a wave.
(i) Determine the frequency of the wave.(Answered) Water waves are observed as they pass a fixed point at a rate of
30 crests per minute. A particular wave crest takes 2s to travel between two fixed points 6m apart.
Determine for the wave:
(i) The frequency
(ii) The wavelength(Answered) Give one example of a transverse wave and one example of longitudinal wave(Answered) Calculate the wavelength of the KCB FM radio wave transmitted at a frequency of 95.6 Mega Hertz.(Answered) State two distinctions between the way sound waves and electromagnetic waves are transmitted(Answered) What is the difference between longitudinal and transverse waves?(Answered) 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 between A and B is constant.(Answered) Two boxes E and F of masses 2.0kg and 4.0kg respectively are dragged along a frictionless surface using identical forces. State with a reason which box moves with a higher velocity.(Answered) Using the definition of impulsive force, show that F=ma.(Answered) A horizontal force of 12N is applied on a wooden block of mass 2kg placed on a
horizontal surface. It causes the block to accelerate at 5 #ms^-2#. Determine the frictional force between the block and the surface.(Answered) A parachute falling through the air attains terminal velocity after a short time. State the
the reason why it attains terminal velocity(Answered) A student pulls a block of the wood along a horizontal surface by applying a constant force. State the reason why the block moves at a constant velocity.(Answered) Figure 13 shows a frictionless trolley of mass 2kg moving with uniform velocity
towards a wall. At the front of the trolley is a spring whose spring constant is 25 Nm-1. The
trolley comes to rest momentarily after compressing the spring by 3cm and the rebounds from the wall.
(i) Determine:
(I) The force exerted on the wall by the spring.
(II) The maximum acceleration of the as it rebounds from the(Answered) Figure 12 shows a lorry towing a trailer using a rope.
The lorry exerts a force N on the trailer and the trailer exerts an equal but opposite force M on the lorry. The frictional force between the trailer and the road is F.
Explain how the forces N, M and F enable the trailer to move.(Answered) Figure 5 is a graph of net force on a body against its velocity as it falls through a liquid.
Determine the terminal velocity of the body(Answered) A cart of mass 30kg is pushed along a horizontal path by a horizontal force of 8N and moves with a constant velocity. The force is then increased to 14N.
Determine:
(a) The resistance to the motion of the cart
(b) The acceleration of th cart.(Answered) A car of mass 800kg starts from rest and accelerates at 1.2 #ms^-2#.
Determine its momentum after it has moved 400m from the starting point(Answered) State newton’s first law of motion.(Answered) A footballer kicks a ball of mass 0.6 kg initially at rest using a force of 720N. if the
foot was in contact with the ball for 0.1 seconds, what was the takeoff speed of the ball?(Answered) A trolley is moving at a uniform speed along a track. A piece of plasticine is dropped on the trolley and sticks on it. Explain why the trolley slows down.(Answered) A resultant force F acts on a body of mass m causing an acceleration #a1# on the body. When the same force acts on a body of mass 2m, it causes an acceleration #a_2#. Express #a_2# in terms of #a_1#(Answered) A body resting on a horizontal surface is given an initial velocity V so that it slides on the
surface for some distance before coming to a stop. Table 1 shows the distance d moved by the body of various values of V.
Given that #V^2# = 20μd where μ is a constant for the surface, plot an appropriate graph and use it to determine μ.(Answered) State one of the Newton’s law of motion(Answered) A high jumper usually lands on thick soft mattress. Explain how the mattress helps in reducing the force of impact.(Answered) A train of mass 200 tonnes starts from rest and accelerates uniformly at 0.5 #ms^-2#.
Determine its momentum after moving 100m(Answered) Two identical spherical steel balls are released from the top of two tall jars containing liquids L1 and L2 respectively. Figure 3 shows the velocity – time graph of the motion of the balls.
Explain the nature of the curves and state why they are different(Answered) An industrial trolley of mass 20kg carrying a mass of 50kg is acted on by a constant force. The trolley moves along a horizontal smooth surface with an acceleration of 0.5 #ms^-2#. Determine the acceleration of the trolley after the mass falls off.(Answered) A gun is fired vertically upwards from the top of an open truck moving horizontally at a uniform velocity of #50 ms^-1#. The bullet achieves a maximum height of 45m.
(i) State with reason whether or not the bullet will land on the truck.
(ii) Calculate the distance covered by the truck just before the bullet reaches the level from
which it was fired. (Use g=10 #ms^-2#).(Answered) A trolley is moving at constant speed in friction compensated track. Some plasticine is dropped on the trolley and sticks on it. State with a reason what is observed about the motion of the trolley.(Answered) State Newton’s first law of motion.(Answered) State and explain the function of the Grid in the cathode ray tube.(Answered) The current of electrons hitting the screen of a cathode ray oscilloscope is 2.0 X #10^-4#A. Determine the number of electrons that strike the screen each second. (Take charge of an electron as 1.6 X#10^-19#C).(Answered) Explain how electrons are produced in the Cathode ray tube.(Answered) State two differences between cathode rays and electromagnetic radiations.(Answered) Figure 14 (a) is a diagram of a cathode ray tube. M and N are parallel vertical plates
(a) When switch S is open, a spot is seen at the centre of the screen as shown in figure 14(b).
(i) State what happens to the sport when S is closed.
(ii) State what would happen to the spot if the potential difference across MN is increased.
(iii) State what would be seen on the screen if the battery is replace(Answered) (a) Figure 14 shows the features of a cathode ray tube.
(i) Name the parts labeled A and B.
(ii) Explain how the electrons are produced in the tube.
(iii) State two functions of the anodes.
(iv) At what part of the cathode ray tube would the time be connected?
(v) Why is a vacuum created in the tube?(Answered) Figure 6 shows a tube for investigating the properties of a beam of electrons. Use the information in the figure to answer question 8. What property of the beam of electrons shows that the electrons are travelling at a very high speed?(Answered) Figure 3 shows the main features of a cathode ray tube (CRT) of a cathode ray oscilloscope (CRO).
(i) Describe how the electrons are produced in the tube.
(ii) State and explain the function of the grid.
(iii) State what would be observed on the screen if an a.c voltage is connected across the y-plates.
(iv) State how the deflection system of a television differs from that of a CRO.
(Answered)