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Some water evaporates from the surface of porous pot and absorbs latent heat of vaporization from the water in the pot, hence the cooling.
sharon kalunda answered the question on September 27, 2019 at 05:48
- A stone of mass 4kg is thrown upwards with a kinetic energy of 240J. Neglecting air resistance,calculate the height to which it will rise. (Take...(Solved)
A stone of mass 4kg is thrown upwards with a kinetic energy of 240J. Neglecting air resistance,calculate the height to which it will rise. (Take g = 10N/kg)
Date posted: September 27, 2019. Answers (1)
- The figure below shows a pulley system for lifting heavy objects.(Solved)
The figure below shows a pulley system for lifting heavy objects.
(i) State the velocity ratio of the pulley system.
(ii) If the efficiency of the machine is 75%, calculate the mechanical advantage of the system.
(iii) Determine the effort applied
Date posted: September 27, 2019. Answers (1)
- Define a machine.(Solved)
Define a machine.
Date posted: September 27, 2019. Answers (1)
- The figure below shows the starting of motion of two arrows 10M above the ground. Both arrows were shot with initial velocity of 20m/s, from...(Solved)
The figure below shows the starting of motion of two arrows 10M above the ground. Both arrows were shot with initial velocity of 20m/s, from one point and at the same instant.
(i) Determine the total height reached by the arrow shot vertically.
(ii) Calculate the time of flight taken by the arrow shot horizontally as it strikes the ground.
(iii) Calculate the horizontal distance covered by the arrow shot horizontally as it strikes the ground.
Date posted: September 26, 2019. Answers (1)
- A turntable of radius 10cm is rotating at 43 revolutions per second. Determine the linear speed of a point on the circumference of the turntable.(Solved)
A turntable of radius 10cm is rotating at 43 revolutions per second. Determine the linear speed of a point on the circumference of the turntable.
Date posted: September 26, 2019. Answers (1)
- A block measuring 20cm by 10cm by 4 cm rests on a flat surface. The block has a weight of 6.0N. Determine:(Solved)
A block measuring 20cm by 10cm by 4 cm rests on a flat surface. The block has a weight of 6.0N. Determine:
(a) The minimum pressure it exerts on the surface.
(b) The density of the block in kg/m3. Take (g = 1N/kg)
Date posted: September 26, 2019. Answers (1)
- A metal iron has work function of 6.8 x 10-19J. Calculate the minimum frequency of light that can cause photoelectric emission. (Take h = 6.63...(Solved)
A metal iron has work function of 6.8 x 10-19J. Calculate the minimum frequency of light that can cause photoelectric emission. (Take h = 6.63 x 10-34 Js)
Date posted: September 26, 2019. Answers (1)
- A solid displaces 5.0cm3 of paraffin when floating and 20cm3 when fully immersed in it. Given that the density of paraffin is 0.8g/cm3 ....(Solved)
A solid displaces 5.0cm3 of paraffin when floating and 20cm3 when fully immersed in it. Given that the density of paraffin is 0.8g/cm3 . Calculate the density of the solid
Date posted: September 26, 2019. Answers (1)
- A submarine made of iron was observed to float in water while a piece of iron rod sinks in water. Explain this observation(Solved)
A submarine made of iron was observed to float in water while a piece of iron rod sinks in water. Explain this observation
Date posted: September 26, 2019. Answers (1)
- A jet of water emerges from a hose pipe of cross-sectional area 5.0 x 10-3m2 with a velocity of 3.0m/s. The water strikes a wall...(Solved)
A jet of water emerges from a hose pipe of cross-sectional area 5.0 x 10-3m2 with a velocity of 3.0m/s. The water strikes a wall at a right angle and comes to rest without rebounding. Determine the mass of water striking the wall per second (Density of water is 1000 kgm-3)
Date posted: September 26, 2019. Answers (1)
- The diagram below shows two horizontal pipes, A and B. Tube A contains liquid at rest while tube B contains liquid in motion.(Solved)
The diagram below shows two horizontal pipes, A and B. Tube A contains liquid at rest while tube B contains liquid in motion
Sketch graphs for (a) and (b) to show variation in pressure
Date posted: September 26, 2019. Answers (1)
- A uniform 1m wooden bar with uniform cross-sectional area of 2.5cm by 2.5cm is suspended at the 60cm mark and kept balanced by hanging a...(Solved)
A uniform 1m wooden bar with uniform cross-sectional area of 2.5cm by 2.5cm is suspended at the 60cm mark and kept balanced by hanging a mass 450g at 100cm mark.
(i) The density of the material of the metre rule
(ii) The tension T in the string
Date posted: September 26, 2019. Answers (1)
- In using the lift pump to raise water from a bore hole. It is observed that practically the height the water is raised cannot be...(Solved)
In using the lift pump to raise water from a bore hole. It is observed that practically the height the water is raised cannot be 10m and more. Give two reasons for this observation.
Date posted: September 26, 2019. Answers (1)
- The load carried by a truck loader was measured to be 65,000 grams. Convert the mass of the load into milligrams and express the answer...(Solved)
The load carried by a truck loader was measured to be 65,000 grams. Convert the mass of the load into milligrams and express the answer in standard form.
Date posted: September 26, 2019. Answers (1)
- With an aid of a labeled diagram, describe an experiment to verify Charles’ law.(Solved)
With an aid of a labeled diagram, describe an experiment to verify Charles’ law.
Date posted: September 26, 2019. Answers (1)
- In an experiment to determine the specific latent heat of vaporization of water, steam at 100ºC was passed into water contained in a well-lagged copper...(Solved)
In an experiment to determine the specific latent heat of vaporization of water, steam at 100ºC was passed into water contained in a well-lagged copper calorimeter. The following measurements were made:
- Mass of calorimeter = 55g
- Initial mass of water = 75g
- Final mass of calorimeter + water + condensed steam = 133g
- Final temperature of the mixture = 30ºC
[Specific heat capacity of water = 4200JKgˉ¹kˉ¹ and specific heat capacity of copper= 390JKgˉ¹kˉ¹]
(i) mass of condensed steam.
heat gained by the calorimeter and water if the initial temperature of the
calorimeter + water = 20ºC.
(ii) given that L is the specific latent heat of vaporization of steam,
(I) Write an expression for the heat given out by steam.
(II) Determine the value of L.
Date posted: September 26, 2019. Answers (1)
- The figure below shows an inclined plane, a trolley of mass 30kg is pulled up a slope by a force of 100N, parallel to the...(Solved)
The figure below shows an inclined plane, a trolley of mass 30kg is pulled up a slope by a force of 100N, parallel to the slope. The trolley moves so that the centre of mass C travels from points A to B.
(i) What is the work done on the trolley against the gravitational force in moving from A to B.?
(ii) Determine the work done by the force in moving the trolley from A to B.
(iii) Determine the efficiency of the system.
(iv) Determine the work done in overcoming the frictional force.
(v) Determine the mechanical advantage of the system.
Date posted: September 26, 2019. Answers (1)
- The figure shows masses X, Y and Z placed at different points on a turn table. The turn table is rotated at different angular velocities.(Solved)
The figure shows masses X, Y and Z placed at different points on a turn table. The turn table is rotated at different angular velocities.
(i) State two factors that would cause the masses to slide.
(ii) At the time that start sliding off, state the mass with the highest angular velocity,give reason for your answer.
Date posted: September 26, 2019. Answers (1)
- In an experiment to determine the density of a liquid, the following readings were made.
Mass of empty density bottle = 20g
Mass of bottle filled with...(Solved)
In an experiment to determine the density of a liquid, the following readings were made.
Mass of empty density bottle = 20g
Mass of bottle filled with water = 70g
Mass of bottle filled with a liquid = 695g
a. Find the density of the liquid, given that density of water is 1000kgmˉ³.
b. Find the mass of the liquid.
Date posted: September 26, 2019. Answers (1)
- The figure below shows a uniform triangular lamina.Locate the centre of gravity of lamina.(Solved)
The figure below shows a uniform triangular lamina.Locate the centre of gravity of lamina.
Date posted: September 26, 2019. Answers (1)