The shiny surface acts as a poor radiation emitters hence reduced heat loss this differs from the dark surface or the dull surfaces on the electric kettle.
jim items answered the question on February 25, 2019 at 17:17
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Explain why metallic materials are better conductors of heat than non- metallic materials
(Solved)
Explain why metallic materials are better conductors of heat than non- metallic materials.
Date posted:
February 23, 2019
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Answers (1)
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Heat transfer in fluids is by convection. Give the molecular explanation of conversation in fluids
(Solved)
Heat transfer in fluids is by convection. Give the molecular explanation of conversation in fluids.
Date posted:
February 23, 2019
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Answers (1)
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A pin hole camera forms an image of size 5 cm tall for an object placed 25 cm tall for an object placed 25 cm away from pinhole.if...
(Solved)
A pin hole camera forms an image of size 5 cm tall for an object placed 25 cm tall for an object placed 25 cm away from pinhole.if the height of the object is 5 cm. Find the length of the pin hole camera.
Date posted:
February 23, 2019
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Answers (1)
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How many images would be seen from two mirrors when reflecting surfaces make an angle of 60 degree with each other?
(Solved)
How many images would be seen from two mirrors when reflecting surfaces make an angle of 60 degree with each other?
Date posted:
February 23, 2019
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Answers (1)
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Explain 2 main branches of physics
(Solved)
Explain 2 main branches of physics.
Date posted:
February 20, 2019
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Answers (1)
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State one difference between ultra-violet rays and X-rays.
(Solved)
State one difference between ultra-violet rays and X-rays.
Date posted:
February 17, 2019
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Answers (1)
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State two safety precautions that should be observed when using electrical hand tools.
(Solved)
State two safety precautions that should be observed when using electrical hand tools.
Date posted:
February 13, 2019
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Answers (1)
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A fishing boat is at rest on sea water with a steel anchor over the side. Explain what would happen to the volume of displaced...
(Solved)
A fishing boat is at rest on sea water with a steel anchor over the side. Explain what would happen to the volume of displaced water by the boat when:
a) the anchor is lowered and left hanging in water
b) the anchor rests on the bed at the sea.
Date posted:
February 13, 2019
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Answers (1)
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A transformer of 480 turns in the primary coil is used to connect a 9V a.c electric device to a 240V a.c mains supply. Calculate...
(Solved)
A transformer of 480 turns in the primary coil is used to connect a 9V a.c electric device to a 240V a.c mains supply. Calculate the number of turns in the secondary coil.
Date posted:
February 12, 2019
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Answers (1)
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A transformer in a welding machine supplies 6V from a 240V mains supply. If the current used in the welding is 30A. Determine the current...
(Solved)
A transformer in a welding machine supplies 6V from a 240V mains supply. If the current used in the welding is 30A. Determine the current in the mains.
Date posted:
February 12, 2019
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Answers (1)
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A body weighs 32N in kerosene and 30N in water. If the body weighs 40N in air, find the relative density of kerosene.
(Solved)
A body weighs 32N in kerosene and 30N in water. If the body weighs 40N in air, find the relative density of kerosene.
Date posted:
February 11, 2019
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Answers (1)
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Define angular displacement and state its unit.
(Solved)
Define angular displacement and state its unit.
Date posted:
February 10, 2019
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Answers (1)
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A certain transformer steps down mains supply from 240V to 6C. There are 1200 turns in the primary circuit. A bulb of 36W is connected...
(Solved)
A certain transformer steps down mains supply from 240V to 6V. There are 1200 turns in the primary circuit. A bulb of 36W is connected to the secondary circuit. Given that the efficiency of the transformer is 100% determine:
a) The number of turns in the secondary circuit.
b) The current in the primary circuit.
Date posted:
February 6, 2019
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Answers (1)
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A metal block of density 7.8g/cm3 weighs 117N in air. Find the weight of the block when fully immersed in water of density 1.0g/cm3.
(Solved)
A metal block of density 7.8g/cm3 weighs 117N in air. Find the weight of the block when fully immersed in water of density 1.0g/cm3.
Date posted:
February 2, 2019
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Answers (1)
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a) An object of mass 0.60kg tied to the end of a rope is whirled in a horizontal circle of radius 2.0m with a constant...
(Solved)
a) An object of mass 0.60kg tied to the end of a rope is whirled in a horizontal circle of radius 2.0m with a constant speed of 10m/s. Find the tension in the string.
Date posted:
February 1, 2019
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Answers (1)
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What do you understand by the term angular velocity?
Deduce the relationship between the linear speed and angular velocity.
(Solved)
What do you understand by the term angular velocity?
Deduce the relationship between the linear speed and angular velocity.
Date posted:
January 31, 2019
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Answers (1)
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An object floats in sea water of density 1.03x10^3kg/m^3. It displaces 260m^3 of sea water. Find the mass of the object.
(Solved)
An object floats in sea water of density 1.03x10^3kg/m^3. It displaces 260m^3 of sea water. Find the mass of the object.
Date posted:
January 30, 2019
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Answers (1)
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A sling of length 1m and holding a stone of mass 200g at its free end is whirled in a horizontal plane such that it...
(Solved)
A sling of length 1m and holding a stone of mass 200g at its free end is whirled in a horizontal plane such that it completes 10 revolutions in 5 seconds. Determine:
a) Tension in the sling
b) The frequency of rotation
c) The velocity with which the stone clips off when released
Date posted:
January 30, 2019
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Answers (1)
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A particle revolves at 2Hz in a circle of radius 2m. Calculate its linear speed and angular velocity.
(Solved)
A particle revolves at 2Hz in a circle of radius 2m. Calculate its:
a) Linear speed
b) Angular velocity
Date posted:
January 29, 2019
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Answers (1)
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A bucket of water containing water is rotated in a vertical circle of radius 80cm. What should its velocity be so that the water may...
(Solved)
A bucket containing water is rotated in a vertical circle of radius 80cm. What should its velocity be so that the water may not spill out?
Date posted:
January 28, 2019
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Answers (1)