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(a) By strongly illuminating a suspension of pollen grains in water/dust particles in air or smoke cell
(b) A body continues in its state of rest or motion with uniform velocity unless acted upon by an external force
Wilfykil answered the question on October 1, 2019 at 05:59
- The five-tick tape shown below was produced by a ticker timer connected to mains supply of 50Hz when a force pulls the trolley.(Solved)
The five-tick tape shown below was produced by a ticker timer connected to mains supply of 50Hz when a force pulls the trolley.
Determine the acceleration of the trolley.
Date posted: September 30, 2019. Answers (1)
- The machine represented in the diagram can be used to lift water from a well.(Solved)
The machine represented in the diagram can be used to lift water from a well.
A force of 50N applied on the handle lifts water of weight 180N
i) Calculate the efficiency of the machine.
ii) Give a reason why the efficiency is less than 100%.
Date posted: September 30, 2019. Answers (1)
- A block of metal of mass 250g at 100°C is dropped into a lagged calorimeter of heat capacity 40J/K containing 100g of water at 25°C....(Solved)
A block of metal of mass 250g at 100°C is dropped into a lagged calorimeter of heat capacity 40J/K containing 100g of water at 25°C. The temperature of the resulting mixture was found to be 40°C. Determine; (Cw = 4200J/k)
i) Heat gained by calorimeter.
ii) Heat gained by water.
iii) Heat lost by the block.
iv) Specific heat capacity of the metal block.
Date posted: September 30, 2019. Answers (1)
- In an experiment, it was observed that soapy water placed on a wet smooth surface displaced the particles of non-soapy water. Sate and explain this...(Solved)
In an experiment, it was observed that soapy water placed on a wet smooth surface displaced the particles of non-soapy water. Sate and explain this observation.
Date posted: September 30, 2019. Answers (1)
- Give one reason why a lift pump raises water to heights less than 10m.(Solved)
Give one reason why a lift pump raises water to heights less than 10m.
Date posted: September 30, 2019. Answers (1)
- A mass of 80kg is being lifted by a force F applied on the other piston of the machine as shown in the figure...(Solved)
A mass of 80kg is being lifted by a force F applied on the other piston of the machine as shown in the figure below.Determine the value of F needed to just lift the 80kg mass given the density of the liquid is 1.2g/cm³.
Date posted: September 30, 2019. Answers (1)
- The figure below shows a drop of fatty acid on a wire of diameter 1.4mm(Solved)
The figure below shows a drop of fatty acid on a wire of diameter 1.4mm
When the drop of the fatty acid was placed on clean water surface it formed a circular patch of diameter 91cm.
i) Estimate the length of the molecule of the fatty acid.
ii) State the assumption made in part (i) above.
Date posted: September 30, 2019. Answers (1)
- The arrangement in the figure below was used to determine the specific heat capacity of the metal.(Solved)
The arrangement in the figure below was used to determine the specific heat capacity of the metal.
State the precautions that need to be taken.
Date posted: September 30, 2019. Answers (1)
- A boy poured some boiling water into a plastic can and placed an air-tight cork on its open end. He then ran some cold water...(Solved)
A boy poured some boiling water into a plastic can and placed an air-tight cork on its open end. He then ran some cold water on it for about 20 seconds after which he shook the can vigorously. State and explain what he observed.
Date posted: September 30, 2019. Answers (1)
- State the law represented in figure below.(Solved)
State the law represented in figure below.
Date posted: September 30, 2019. Answers (1)
- State the contribution physics has made to the entertainment industry.(Solved)
State the contribution physics has made to the entertainment industry.
Date posted: September 30, 2019. Answers (1)
- The figure below shows a uniform bar of weight 5N and length 1.1m pivoted at a point and in equilibrium under the action of the...(Solved)
The figure below shows a uniform bar of weight 5N and length 1.1m pivoted at a point and in equilibrium under the action of the forces shown.
Determine the value of weight W.
Date posted: September 30, 2019. Answers (1)
- Two forces are acting on a body as shown in the figure below. By use of a vector, draw the body and show the resultant...(Solved)
Two forces are acting on a body as shown in the figure below. By use of a vector, draw the body and show the resultant force.
Date posted: September 30, 2019. Answers (1)
- The figure below shows a graph showing the behaviour of a helical spring.(Solved)
The figure below shows a graph showing the behaviour of a helical spring.
Determine the spring constant in SI units.
Date posted: September 30, 2019. Answers (1)
- The water level in a burette is 30.6cm³, 50 drops of water each of volume 0.2cm³ are added to the water in the burette. What...(Solved)
The water level in a burette is 30.6cm³, 50 drops of water each of volume 0.2cm³ are added to the water in the burette. What is the final reading of the burette.
Date posted: September 30, 2019. Answers (1)
- A transformer with 1200 turns in the primary circuit and 120 turns in the secondary circuit has its primary circuit connected to a 400V a.c....(Solved)
A transformer with 1200 turns in the primary circuit and 120 turns in the secondary circuit has its primary circuit connected to a 400V a.c. source. It is found that when a heater is connected to the secondary circuit, it produces heat at the rate of 600W. Assuming 100% efficiency, determine the:
i) voltage in the secondary circuit.
ii) current in the primary circuit.
iii) current in the secondary circuit.
Date posted: September 30, 2019. Answers (1)
- The cost of electricity per kilowatt hour- kWh is Ksh.8, determines how much a household running a device rated 1500W continuously for 1.08 x 105...(Solved)
The cost of electricity per kilowatt hour- kWh is Ksh.8, determines how much a household running a device rated 1500W continuously for 1.08 x 105 seconds, would pay.
Date posted: September 30, 2019. Answers (1)
- A uniform resistance wire of length 2.0m conducts a current of 0.25A when connected in series with a cell of e.m.f of 1.6V. How much...(Solved)
A uniform resistance wire of length 2.0m conducts a current of 0.25A when connected in series with a cell of e.m.f of 1.6V. How much current would be conducted if the wire is now cut into 2 equal lengths which are then arranged in parallel.
Date posted: September 30, 2019. Answers (1)
- Diagram below represents a metre bridge used to determine the resistance of an electrical component, X.(Solved)
Diagram below represents a metre bridge used to determine the resistance of an electrical component, X.
From the diagram,
i) Explain why wide brass strips are used as terminals.
ii) Explain why a cell of low e.m.f is preferable.
iii) If null deflection was obtained when l1 was 60.0cm. Calculate the resistance of component marked X.
iv) State three ways of ensuring that the error is minimized.
Date posted: September 30, 2019. Answers (1)
- Diagram below is a resistor-capacitor circuit. At time t = 0, the switch is closed at A for some time and then opened. The switch...(Solved)
Diagram below is a resistor-capacitor circuit. At time t = 0, the switch is closed at A for some time and then opened. The switch is then closed at B for some time.
On the axes provided below, sketch graph of voltage V across the capacitor against time t (t1 and t2 represent time for opening at A and closing at B respectively).
Date posted: September 30, 2019. Answers (1)