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Work is said to be done when the body on which a force is applied moves in the direction
of force; S.I unit if the Joule, J or (Nm);
sharon kalunda answered the question on April 2, 2019 at 08:56
- A man uses a block and tackle mechanism of velocity ratio 6 to lift a car engine smoothly through a height of 1 m in...(Solved)
A man uses a block and tackle mechanism of velocity ratio 6 to lift a car engine smoothly through a height of 1 m in 5s. The man applies a force of 300N while the mass of the engine is 120 kg. Determine:
(i) The mechanical advantage of the pulley system.
(ii) its efficiency.
Date posted: April 2, 2019. Answers (1)
- A bicycle has wheels 66 cm in diameter. Its crank wheel has 44 teeth and the rear sprocket 16 teeth. The crank radius is 16.5...(Solved)
A bicycle has wheels 66 cm in diameter. Its crank wheel has 44 teeth and the rear sprocket 16 teeth. The crank radius is 16.5 cm.
(i) Determine the radius of the rear sprocket.
(ii) The bicycle moves when the rear sprocket is made to move. Hence determine the
velocity ratio.
Date posted: April 2, 2019. Answers (1)
- A wheel and axle are used to raise a load of 280N by a force 40N applied to the rim of the
wheel. If the radii...(Solved)
A wheel and axle are used to raise a load of 280N by a force 40N applied to the rim of the
wheel. If the radii of the rim and axle are 70cm and 5cm respectively, calculate:
(i) The mechanical advantage
(ii) The velocity ratio
(iii) The efficiency
Date posted: April 2, 2019. Answers (1)
- The graph below shows the potential energy against displacement for a body of mass 80 g.(Solved)
The graph below shows the potential energy against displacement for a body of mass 80 g.
The body oscillates about point R. Calculate the velocity of the body at:
(i) P and T
(ii) Q and S
(iii) at R
Date posted: April 2, 2019. Answers (1)
- State the law of conservation of energy(Solved)
State the law of conservation of energy
Date posted: April 2, 2019. Answers (1)
- The diagram below shows a charcoal refrigerator. (i) Explain why charcoal is used and why it is sprinkled with water...(Solved)
The diagram below shows a charcoal refrigerator.
(i) Explain why charcoal is used and why it is sprinkled with water
(ii) What is the role of the metallic tank and the wire mesh
Date posted: April 2, 2019. Answers (1)
- Briefly explain two ways other than direct heating by which quantity of liquid may be made to evaporate more quickly(Solved)
Briefly explain two ways other than direct heating by which quantity of liquid may be made to evaporate more quickly
Date posted: April 2, 2019. Answers (1)
- 0.5kg of naphthalene contained in an aluminium can of mass 0.4kg is melted in a water bath and raised to a temperature of 100oC ....(Solved)
0.5kg of naphthalene contained in an aluminium can of mass 0.4kg is melted in a water bath and raised to a temperature of 100oC . Calculate the total heat given out when the can and its contents are allowed to cool to room temperature, 20oC . Neglect losses by evaporation during heating process and give your answer to the nearest kilojoule.(For naphthalene melting point = 80oC , Specific heat capacity for both liquid and solid =2100J/KgK; specific latent heat of fusion = 170000J/Kg.For aluminium: specific heat capacity = 900J/Kg/k
Date posted: April 2, 2019. Answers (1)
- An electric heater 1KW 240V is used to raise the temperature of a 5kg copper block from 15oC to 33oC. If the specific heat capacity...(Solved)
An electric heater 1KW 240V is used to raise the temperature of a 5kg copper block from 15oC to 33oC. If the specific heat capacity of copper is 400J/Kg/K and assuming no heat is lost to the surrounding,Calculate the time taken.
Date posted: April 2, 2019. Answers (1)
- Explain why steel feels colder than wood at the same temperature.(Solved)
Explain why steel feels colder than wood at the same temperature.
Date posted: April 2, 2019. Answers (1)
- Figure below shows a test tube partially filled with water. An ice wrapped in wire gauze is placed at the bottom of the test-tube. It...(Solved)
Figure below shows a test tube partially filled with water. An ice wrapped in wire gauze is placed at the bottom of the test-tube. It is then held in the flame of a bunsen burner as shown below
State and explain what will be observed after some time
Date posted: April 2, 2019. Answers (1)
- The figure below shows two identical thermometers. Thermometer A has a blackened bulb while thermometer B has a silvery bulb. A candle is placed equidistant between...(Solved)
The figure below shows two identical thermometers. Thermometer A has a blackened bulb while thermometer B has a silvery bulb. A candle is placed equidistant between the two thermometers.
State with a reason the observations made after some time
Date posted: April 2, 2019. Answers (1)
- Figure below shows a cross-section of a vacuum flask (i) Name the parts labelled A and B on the diagram...(Solved)
Figure below shows a cross-section of a vacuum flask
(i) Name the parts labelled A and B on the diagram
(ii) Explain how the heat losses are minimized when hot liquid is poured into the flask
Date posted: April 2, 2019. Answers (1)
- A jet delivering 0.44g of dry steam per second, at 100oC is directed on to crushed ice at 0.0oC contained in an unlagged copper can...(Solved)
A jet delivering 0.44g of dry steam per second, at 100oC is directed on to crushed ice at 0.0oC contained in an unlagged copper can which has a hole in the base. 4.44g of water at 0.0oC flow out of the hole per second.
(i) How many joules of heat are given out per second by condensing steam and cooling to 0.0oC of water formed?(Latent heat of vaporization of steam = 2.26 x 106JKg-1,c for water = 4200JKg-1K-1)
(ii) How much heat is taken in per second by the ice which melts?
(iii) Suggest why these amounts above are different
Date posted: April 2, 2019. Answers (1)
- A block of metal of mass 150g at 100oC is dropped into a logged calorimeter of heat capacity
40J/k containing 100g of water at 25oC. The...(Solved)
A block of metal of mass 150g at 100oC is dropped into a logged calorimeter of heat capacity
40J/k containing 100g of water at 25oC. The temperature of the resulting mixture is 34oC.
(Specific heat capacity of water = 4200J/KgK)
Determine;-
(i) Heat gained by calorimeter
(ii) Heat gained by water
(iii) Heat lost by the metal block
(iv) Specific heat capacity of the metal block
Date posted: April 2, 2019. Answers (1)
- 200g of a solid was uniformly heated by a 0.2 kw heater for sometime. The graph in the figure below shows how the temperature of...(Solved)
200g of a solid was uniformly heated by a 0.2 kw heater for sometime. The graph in the figure below shows how the temperature of the solid changed with time.
(i) Explain what is happening between OA and AB.
(ii) Calculate the specific heat capacity of the solid.
(iii) Calculate the specific latent heat of fusion k of the solid.
Date posted: April 2, 2019. Answers (1)
- A block of metal of mass 300g at 1000c is dropped into a logged calorimeter of heat capacity40Jk-1, containing 200g of water at 200c. The...(Solved)
A block of metal of mass 300g at 1000c is dropped into a logged calorimeter of heat capacity40Jk-1, containing 200g of water at 200c. The temperature of the resulting mixture is 340c
Determine:
(i) Heat gained by calorimeter.
(ii) Heat gained by water.
(iii) Heat lost by the metal block.
(iv) Specific heat capacity of the metal block.
Date posted: April 2, 2019. Answers (1)
- A mass of 2kg is attached to a string of length 50 cm. It is whirled in a circle in a vertical plane
at 10 revolution...(Solved)
A mass of 2kg is attached to a string of length 50 cm. It is whirled in a circle in a vertical plane
at 10 revolution per second about a horizontal axis. Calculate the tension in the string when the
mass is at the :-
(a)Highest point of the circle.
(b) Lowest part of the circle.
Date posted: April 2, 2019. Answers (1)
- A wooden block of mass 200g is placed at various distances from the center of a turntable,which is rotating at constant angular velocity. It is...(Solved)
A wooden block of mass 200g is placed at various distances from the center of a turntable,which is rotating at constant angular velocity. It is found that at a distance of 8.0cm from the center, the block just starts to slide off the table. If the force of friction between the block and the table is 0.4N, Calculate:
(i) The angular velocity of the table
(ii) The force required to hold the block at a distance of 12cm from the center of the table
Date posted: April 2, 2019. Answers (1)
- A small pendulum bob having a mass of 150g is suspended by an inelastic string of length 0.5m. The mass is made to rotate in...(Solved)
A small pendulum bob having a mass of 150g is suspended by an inelastic string of length 0.5m. The mass is made to rotate in a horizontal circle of radius 0.4m and whose centre is vertically below the point of suspension
(i) Determine the tension in the string
(ii) State one application of the pendulum
Date posted: April 2, 2019. Answers (1)