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A pump uses a mixture of petrol and alcohol in the ratio 4: 1 by mass to raise 100kg of water from a well 200m deep.
i) How much energy is given by 1g of mixture?
ii) If the pump is 40% efficient, what mass of this mixture is needed to raise the water?
Date posted:
March 26, 2019
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An energy saving stove when burning steadily has an efficiency of 60%. The stove melts 0.03kg of ice at 00c in 180 seconds. Calculate; -
i) The power rating of the stove.
ii) The heat energy wasted by the stove.
Date posted:
March 26, 2019
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Give the differences between motivation, satisfaction, inspiration and manipulation.
Date posted:
March 26, 2019
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The products of a burning candle were passed through a tube containing calcium oxide as shown in the diagram below.
(a) Write two chemical equations for the reactions that took place in tube P.
(b) Name two gases that came out through tube R.
Date posted:
March 26, 2019
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An electric heater rated 6000W is used to heat 1kg of ice initially at -100c until all the mass turns to steam. Given that:
Latent heat of fusion =334kJ-1
Specific heat capacity of ice= 2,260J kg -1 K -1
Specific heat capacity of water = 4, 200J kg-1 K-1
Latent heat of vaporization = 2, 260KJ kg -1 K -1
Calculate the minimum time required for this activity.
Date posted:
March 26, 2019
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Excess Carbon (II) Oxide was passed over a heated sample of an oxide of iron as shown in the diagram below. Study the diagram and the data and use it to answer the questions that follow
Mass of empty dish =6.72g
Mass of empty dish + oxide of iron =9.04g
Mass of empty dish + residue=8.40g
(a) Determine the formula of the oxide of iron given that the relative formula mass of oxide of Iron = 232, Fe = 56.0, O=16.0
(b) Write an equation for the reaction which took place in the dish
Date posted:
March 26, 2019
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An electric toy is rated 100W, 240V. Calculate the resistance of the toy when operating normally.
Date posted:
March 26, 2019
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An electrical heater is labelled 120W, 240V. Calculate;
a) The current through the heating element when the heater is on.
b) The resistance of the element used in the heater.
Date posted:
March 26, 2019
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An electrical appliance is rated as 240V, 200W. What does this information mean?
Date posted:
March 26, 2019
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How many 100W electric irons could be safely connected to a 240V moving circuit fitted with a 13A fuse?
Date posted:
March 26, 2019
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When a current of 2A flows in a resistor for 10 minutes, 15KJ of electrical energy is dissipated. Determine the voltage across the resistor.
Date posted:
March 26, 2019
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An electric bulb rated 40W is operating on 240V mains. Determine the resistance of its filament
Date posted:
March 26, 2019
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One range of frequencies used in broadcasting varies from 0.5 x 100 Hz to 2.0 x 107 Hz. What is the longest wavelength of this range? Velocity of light air =3x108/s
Date posted:
March 26, 2019
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Explain the MC Gregor's participation model.
Date posted:
March 26, 2019
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The figure below shows how the potential Energy (P.E) of a ball thrown vertically upwards.
On the same axes, plot a graph of kinetic energy of the ball.
Date posted:
March 26, 2019
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The figure below shows a loaded wheelbarrow. Indicate and label on the diagram three forces acting on the wheelbarrow when a worker is just about to lift the handle.
Date posted:
March 26, 2019
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The diagram below is a cross section of a dry cell. Study it and answer the questions that follow.
(i) Write the equation for the reaction in which electrons are produced.
(ii) The Zinc can is lined with Ammonium Chloride and Zinc Chloride paste. What would happen if the mixture was to become dry? Give reason.
Date posted:
March 26, 2019
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A body has 16 Joules of kinetic energy. What would be its kinetic energy if its velocity was double?
Date posted:
March 26, 2019
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A workshop has the following simple machines for lifting heavy loads, a wheel and axle, and a movable pulley. The wheel has a diameter of 30cm while the axle has diameter of 3.0cm.
i) Sketch force diagrams to show how each machine works.
ii) Assuming that the machines are perfect. Calculate the mechanical advantage for each of the machines and show which machine is more advantageous in lifting loads.
Date posted:
March 26, 2019
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A car of mass 800 kg is initially moving at 25 m/s. Calculate the force needed to bring the car to rest over a distance of 20 m.
Date posted:
March 26, 2019
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A ball rolls on a table in a straight line. A part from the transitional kinetic energy, state the other form of kinetic energy possessed by the ball.
Date posted:
March 26, 2019
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A pump uses 1g of a mixture of petrol and alcohol in the ratio 4:1 by mass to raise 1000 kg of water from a well 200m deep.
i) How much energy is given by 1g of mixture?
ii) If the pump is 40% efficient, what mass of this mixture is needed to raise the water? (1g of alcohol = 7000J, of petrol= 48000J)
Date posted:
March 26, 2019
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An energy saving stove when burning steadily has an efficiency of 69%. The stove melts 0.03 kg lf ice 00C in 180 seconds.
Calculate: -
i) The power rating of the stove.
ii) The heat energy wasted by the stove.
Date posted:
March 26, 2019
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Figure below shows a block of mass 30.0 kg being pulled up a slope by force P at a constant speed. The frictional force on the block is 20.0N
i) On the same figure name and indicate other forces acting on the block.
ii) Determine the component of the weight acting on the trolley down the slope
iii) Determine the value of P.
Date posted:
March 26, 2019
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The fig. shows a 2 kg block attached to 0.5 kg mass by a light in-extensible string which passes over a pulley. The force of friction between the horizontal bench and block is 3N. The block is released from rest so that both masses move through a distance of 0.6m. Calculate the velocity of the string.
Date posted:
March 26, 2019
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In figure shown below. Two identical electroscopes A and B carry the same type of charges as shown. The two are then connected with a copper wire.
State and explain the observations made.
Date posted:
March 26, 2019
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A body of mass 5 kg is ejected vertically from the ground when a force of 600N acts on it for 0.1s. Calculate the velocity with which the body leaves the ground.
Date posted:
March 26, 2019
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Two coins were placed at the bottom of two jars each containing a different clear liquid as shown in figure below.
The liquids in the two jars are at the same level. The coin in jar q appears shallower than that in jar P. Explain.
Date posted:
March 26, 2019
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A girl of mass 40 kg stands on a scale balance in a lift. The lift is upwards. At one instant the acceleration of the lift is 2m/s. Calculate the reading on the scale at that instant.
Date posted:
March 26, 2019
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Two masses of 3kg and 7kg are connected by a light string. The 3kg mass rests on a smooth incline plane 300 to the horizontal. The 7kg mass hangs freely from the friction-less pulley attached to the top of plane.
i) Draw a diagram showing the bodies and identify the forces acting on the 3 kg mass.
ii) Calculate the acceleration of the masses.
Date posted:
March 26, 2019