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An electric kettle with a 2.0kw heating element has a heat capacity of 400j/k. 1.0kg of water at 20°C is placed in the kettle. The...
(Solved)
An electric kettle with a 2.0kw heating element has a heat capacity of 400j/k. 1.0kg of water at 20°C is placed in the kettle. The kettle is switches on and it is found that 13 minutes later the mass of water in it is 0.5kg. Ignoring heat losses ; calculate
i) Total heat supplied.
ii) Heat used for the kettle.
iii) Heat used to raise temperature of 1kg of water from 20°C to 100°C.
iv) Heat to change water at 100°C to steam at 100°C.
v) The specific latent heat of vaporization of water.
Date posted:
May 31, 2019
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Answers (1)
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A glass capillary contains enclosed air by a thread of mercury 15cm long when the tube is horizontal, the length of the enclosed air column...
(Solved)
A glass capillary contains enclosed air by a thread of mercury 15cm long when the tube is horizontal, the length of the enclosed air column 24cm as shown.
i) What is the length of the enclosed air column when the tube is vertical with the open end uppermost if the atmosphere pressure is 750mmHg?
ii) Explain why the mercury does not run out when the tube is vertical with the closed end uppermost.
Date posted:
May 31, 2019
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Answers (1)
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A car of mass 800g is initially moving at 25m/s. Calculate the force needed to bring the car to rest over a distance of 20m.
(Solved)
A car of mass 800g is initially moving at 25m/s. Calculate the force needed to bring the car to rest over a distance of 20m.
Date posted:
May 31, 2019
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Answers (1)
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A bob of mass 20kg is suspended using a string of 4m from a support and swings through a vertical height of 0.9m as shown...
(Solved)
A bob of mass 20kg is suspended using a string of 4m from a support and swings through a vertical height of 0.9m as shown below:
Determine:
i) The potential energy of the body at its position.
ii) Speed of the body when passing through the lowest point.
Date posted:
May 31, 2019
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Answers (1)
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A cork enclosing steam in a boiler is held down by the system shown.
If the area of the cork is 15 cm2 and a force...
(Solved)
A cork enclosing steam in a boiler is held down by the system shown.
If the area of the cork is 15 cm2 and a force (F) of 500N is needed to keep the cork in place, determine the pressure of the steam in the boiler.
Date posted:
May 31, 2019
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Answers (1)
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In an experiment to determine the thickness of an oil molecule, an oil drop of volume 3.60 x 10-6 m3 was observed to form a...
(Solved)
In an experiment to determine the thickness of an oil molecule, an oil drop of volume 3.60 x 10-6 m3 was observed to form a circular patch of diameter 0.016m on the surface of water covered with lycopodium powder
i). Explain why the oil drop forms a circular patch.
ii) Determine the thickness of the oil molecule
Date posted:
May 31, 2019
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Answers (1)
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The figure below shows a uniform plank AB of length 10m weighing 500N. Two masses measuring 25kg and 60kg are loaded on its ends.
Determine the...
(Solved)
The figure below shows a uniform plank AB of length 10m weighing 500N. Two masses measuring 25kg and 60kg are loaded on its ends.
Determine the distance from point A where a support should be placed for the plank to balance horizontally.
Date posted:
May 31, 2019
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Answers (1)
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A small drop of oil has a volume of 5 × 10-8m³. When it is put on the surface of some clean water, it forms...
(Solved)
A small drop of oil has a volume of 5 × 10-8m³. When it is put on the surface of some clean water, it forms a circular film of 0.1m² in area; what is the size the a molecule oil.
Date posted:
May 31, 2019
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Answers (1)
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The diagram below shows a gas cooker thermostat
Briefly explain how the thermostat works
(Solved)
The diagram below shows a gas cooker thermostat
Briefly explain how the thermostat works
Date posted:
May 31, 2019
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Answers (1)
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The distance between the ice point and steam point on a liquid in glass thermometer is 30cm. what temperature is recorded when the mercury thread...
(Solved)
The distance between the ice point and steam point on a liquid in glass thermometer is 30cm. what temperature is recorded when the mercury thread is 12cm above the ice point?
Date posted:
May 31, 2019
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Answers (1)
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A single spring stretches by 2.0 cm when supporting a load of 50N. If in the system below the springs are identical and have negligible...
(Solved)
A single spring stretches by 2.0 cm when supporting a load of 50N. If in the system below the springs are identical and have negligible weight
Find:
a) The total extension of the system.
b) The total spring constant.
Date posted:
May 31, 2019
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Answers (1)
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The figure below shows an object placed infront of a thin lens. The focal length of the lens is 10cm. The screen is adjusted
until an...
(Solved)
The figure below shows an object placed infront of a thin lens. The focal length of the lens is 10cm. The screen is adjusted
until an image which is magnified 5 times is obtained.
From the information:
a) i) Which type of lens was used in the experiment.
ii) State any other characteristics of the image formed.
iii) Find the value of u.
Date posted:
May 31, 2019
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Answers (1)
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The diagram below shows a micrometer screw gauge used by a student to measure the thickness of a wire. If it has a zero error...
(Solved)
The diagram below shows a micrometer screw gauge used by a student to measure the thickness of a wire. If it has a zero error of 0.06mm, what is the actual thickness of the wire?
Date posted:
May 31, 2019
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Answers (1)
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State two advantages of the use of alternating voltage for the transmission of electrical energy.
(Solved)
State two advantages of the use of alternating voltage for the transmission of electrical energy.
Date posted:
May 31, 2019
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Answers (1)
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A transformer is used to provide a potential difference of 100KV to an X-ray tube from 250V a.c mains supply. A current of 100mA flows...
(Solved)
A transformer is used to provide a potential difference of 100KV to an X-ray tube from 250V a.c mains supply. A current of 100mA flows in ht X-ray tube and the transformer is 100% efficient. Calculate:-
(i) The ratio of the number of turns of the secondary coil to the number of turns in the primary coil.
(ii) The current in the primary coil.
(iii) State giving reasons which of the coils of the transformer is thinner.
Date posted:
May 31, 2019
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Answers (1)
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State one difference and one similarity between a step up transformer and an induction coil.
(Solved)
State one difference and one similarity between a step up transformer and an induction coil.
Date posted:
May 31, 2019
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Answers (1)
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The figure below shows a simple transformer. Study it and answer the questions that follow.
i) Explain why the core is a continuous loop.
ii) Give...
(Solved)
The figure below shows a simple transformer. Study it and answer the questions that follow.
i) Explain why the core is a continuous loop.
ii) Give a reason as to why the core is laminated.
iii) State and explain which coils are thicker.
Date posted:
May 31, 2019
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Answers (1)
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In the figure below the bar magnet is moved into the coil.
(i) State and explain what is observed in the galvanometer.
(ii) Explain briefly the...
(Solved)
In the figure below the bar magnet is moved into the coil.
(i) State and explain what is observed in the galvanometer.
(ii) Explain briefly the source of an electrical energy in the circuit.
Date posted:
May 31, 2019
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Answers (1)
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In an experiment to determine the refractive index of a liquid, the liquid was poured into a measuring cylinder, a pin was
placed at the bottom...
(Solved)
In an experiment to determine the refractive index of a liquid, the liquid was poured into a measuring cylinder, a pin was
placed at the bottom of the cylinder and another pin was used to locate the apparent position of the first pin. The values
of real and apparent depth were used to plot a graph in the figure below.
i) From the graph determine the refractive index of the liquid.
ii) Given that the velocity of light in vacuum is 3.0 x 108 m/s what would be the velocity of light in the liquid
above.
Date posted:
May 31, 2019
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Answers (1)
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The figure below shows an object O placed in front of an objective lens Lo whose focal length fo is less than fe, the focal...
(Solved)
The figure below shows an object O placed in front of an objective lens Lo whose focal length fo is less than fe, the focal length of the eyepiece Le. Complete using ray construction how the arrangement would produce a compound microscope.
Date posted:
May 31, 2019
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Answers (1)