Metal is denser than water. Metal and the piece of wood have a general density (combined density) less than that of water and floats just below the surface.
Wilfykil answered the question on March 27, 2019 at 06:58
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A mass of 120 g half immersed in water displaced a volume of 20 cm3. Calculate the density of the object
(Solved)
A mass of 120 g half immersed in water displaced a volume of 20 cm3. Calculate the density of the object
Date posted:
March 27, 2019
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Answers (1)
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Determine the density of glass that weighs 0.5N in air and 0.3N in water.
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Determine the density of glass that weighs 0.5N in air and 0.3N in water.
Date posted:
March 27, 2019
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Answers (1)
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State how a hydrometer may be used to test whether a car battery is fully charged.
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State how a hydrometer may be used to test whether a car battery is fully charged.
Date posted:
March 27, 2019
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Answers (1)
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A child of mass 20kg sits on a swing of length 4m and swings through a vertical height of 0.9m as shown in the figure...
(Solved)
A child of mass 20kg sits on a swing of length 4m and swings through a vertical height of 0.9m as shown in the figure below.
Determine the:
i) Speed of the child when passing through the lowest point.
ii) Force exerted on the child by the seat of the swing when passing through the lowest point.
Date posted:
March 27, 2019
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Answers (1)
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A body moving with uniform angular velocity found to have covered an angular distance 170 radians in t seconds. Thirteen seconds later it is found...
(Solved)
A body moving with uniform angular velocity found to have covered an angular distance 170 radians in t seconds. Thirteen seconds later it is found to have covered a total angular distance of 300 radians. Determine t
Date posted:
March 27, 2019
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Answers (1)
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A small object moving in a horizontal circle of radius 0.2m makes 8 revolutions per second. Determine its centripetal acceleration.
(Solved)
A small object moving in a horizontal circle of radius 0.2m makes 8 revolutions per second. Determine its centripetal acceleration.
Date posted:
March 27, 2019
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Answers (1)
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The rear wheel of a certain car has a diameter of 40cm. At a certain speed of the car, the wheel makes 7 revolutions per...
(Solved)
The rear wheel of a certain car has a diameter of 40cm. At a certain speed of the car, the wheel makes 7 revolutions per second. A small stone embedded in the tyre tread flies off initially at an angle of 450 to the ground. Determine the initial velocity of the pebble(take pi = 22/7)
Date posted:
March 27, 2019
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Answers (1)
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A light inextensible string of length L is fixed at its upper end and support a mass m at the other end. m is rotated...
(Solved)
A light inextensible string of length L is fixed at its upper end and support a mass m at the other end. m is rotated at horizontal plane or radius r as shown. The maximum tension the string can withstand without breaking is 2N. Assuming the string breaks when the radius is maximum, calculate the velocity of the mass when the string breaks, given that L 1.25m, and m= 0.1kg.
Date posted:
March 27, 2019
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Answers (1)
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Figures (a) and (b) below show diagrams of the human eye.
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Figures (a) and (b) below show diagrams of the human eye.
i) Sketch in figure (a) a ray diagram to show short sightedness.
ii) Sketch in figure (b) a ray diagram to show how a lens can be used to correct the shortsightedness.
Date posted:
March 27, 2019
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Answers (1)
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Describe with the aid of labeled diagram an experiment to determine the focal length of the lens when provided with the following; an illuminated object,...
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Describe with the aid of labeled diagram an experiment to determine the focal length of the lens when provided with the following; an illuminated object, a convex lens, a lens holder, a plane mirror and a metre rule.
Date posted:
March 27, 2019
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Answers (1)
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A vertical object is placed at the focal point F of a diverging lens as shown in figure below.
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A vertical object is placed at the focal point F of a diverging lens as shown in figure below.
Sketch a ray diagram to show the image of the object.
Date posted:
March 27, 2019
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Answers (1)
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Two lenses L1 and L2 placed 12cm from each other. The focal length of L2 is 4cm. An object 5mm high is placed 4cm from...
(Solved)
Two lenses L1 and L2 placed 12cm from each other. The focal length of L2 is 4cm. An object 5mm high is placed 4cm from L1.
i) Construct a scaled ray diagram on a graph paper to obtain the position of the final image as would be observed by a person on
the right hand side of L2
ii) Determine the magnification obtained by the arrangement
Date posted:
March 27, 2019
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Answers (1)
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You are provided with a rectangular glass block, two pins and a piece of white paper. Describe how you would use them to determine the...
(Solved)
You are provided with a rectangular glass block, two pins and a piece of white paper. Describe how you would use them to determine the refractive index of the glass using real and apparent image method
Date posted:
March 27, 2019
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Answers (1)
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The figure below shows how a distant object is focused in a defective eye.
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The figure below shows how a distant object is focused in a defective eye.
i) State the nature of the defect.
ii) Suggest suitable lens to correct the defect.
Date posted:
March 27, 2019
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Answers (1)
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On a certain day when the temperature is 370c, the pressure in an open gas jar is 640mm of mercury. The jar is then sealed...
(Solved)
On a certain day when the temperature is 370c, the pressure in an open gas jar is 640mm of mercury. The jar is then sealed and cooled to the temperature of 170c. Calculate the final pressure.
Date posted:
March 27, 2019
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Answers (1)
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In an experiment to determine the specific latent heat of vaporization of water, steam at 1000c was passed into water contained in a well-lagged copper...
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In an experiment to determine the specific latent heat of vaporization of water, steam at 1000c was passed into water contained in a well-lagged copper calorimeter. The following measurements were made:
Mass of calorimeter = 50g
Initial mass of water = 70g
Final mass of calorimeter + water + condensed steam = 123g
Final temperature of mixture = 300C
(Specific heat capacity of water = 4200 J kg -1K and specific heat capacity for copper = 390 J kg -1 K-1)
Determine the:
i) Mass of condensed steam
ii) Heat gained by the calorimeter and water
iii) Given that L is the specific latent heat of evaporation of steam
I. Write an expression for the heat given out by steam
II. Determine the value of L.
Date posted:
March 26, 2019
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Answers (1)
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An immersion heater rated 90W is placed in a liquid of mass 2kg. When the heater is switched on for 15 minutes, the temperature of...
(Solved)
An immersion heater rated 90W is placed in a liquid of mass 2kg. When the heater is switched on for 15 minutes, the temperature of the liquid rises from 200C to 300C. Determine the specific heat of the liquid.
Date posted:
March 26, 2019
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Answers (1)
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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...
(Solved)
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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Answers (1)
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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)...
(Solved)
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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Answers (1)
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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
(Solved)
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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Answers (1)