The figure below show a uniform metre rule balanced when pivoted at the 30cm mark under the conditions of forces as shown below.Calculate the weight...

The figure below show a uniform metre rule balanced when pivoted at the 30cm mark under the conditions of forces as shown below.

Calculate the weight W of the rule.

---

Taking moments about the pivot point P
Sum of clockwise moment = W x 20 + 0.5 x 40
Sum of anticlockwise moment = 4.8 x 20
20W + 20 = 96
20W = 76
W = 3.8N

---

sharon kalunda answered the question on September 9, 2019 at 06:09

Exams With Marking Schemes

• Grade 1
• Grade 2
• Grade 3
• Grade 4
• Grade 5
• Grade 6
• Grade 7
• Grade 8
• Grade 9
• PP1
• PP2
• Playgroup
• Form 1
• Form 2
• Form 3
• Form 4

Related Questions

---

• The figure below shows water flowing through two sections A and B of a pipe having different cross-sectional area.Indicate and explain the water level in... (Solved)
  

  The figure below shows water flowing through two sections A and B of a pipe having different cross-sectional area.Indicate and explain the water level in manometer B.
  

  Date posted: September 9, 2019 .    Answers (1)

• The figure below shows a U-tube manometer containing a gas, mercury and water. Calculate the gas pressure acting on the mercury. (Take atmospheric pressure to... (Solved)
  

  The figure below shows a U-tube manometer containing a gas, mercury and water. Calculate the gas pressure acting on the mercury. (Take atmospheric pressure to be 1.05 x 10⁵ pa, density of mercury and water to be 13600kg/m³ and 1000kg/m³ respectively).
  

  Date posted: September 9, 2019 .    Answers (1)

• The figure below shows three wooden blocks resting on a flat surface. (They are of the same material). (Solved)
  

  The figure below shows three wooden blocks resting on a flat surface. (They are of the same material).
  
  i) Arrange them starting from the least stable.
  (ii) State the factor that you have considered in (i) above.

  Date posted: September 9, 2019 .    Answers (1)

• The figure below shows an electromagnetic relay being used to switch an electric motor on and off. The electromagnet consists of a coil of wire... (Solved)
  

  The figure below shows an electromagnetic relay being used to switch an electric motor on and off. The electromagnet consists of a coil of wire wrapped around a core. The motor in figure is switched off.
  
  (a) Suggest suitable material for the core.
  (b) What happens to the core when switch S is closed?
  (c) Why do the contacts A and B close when the switch S is closed.
  (d) When the switch S is opened, what will happen to;
  (i) The core
  (ii) Soft iron armature.

  Date posted: September 9, 2019 .    Answers (1)

• The figure below shows a circuit with resistors and voltmeter connected to a battery. (Solved)
  

  The figure below shows a circuit with resistors and voltmeter connected to a battery.
  
  (i) If each cell has an internal resistance of 0.7 ohms, determine the total resistance in the circuit.
  (ii) What amount of current flows through the 3 ohms resistor when the switch is closed?
  (iii) What is the reading of the voltmeter when the switch S is
  (I) Open
  (II) Closed
  (iv) Account for the difference between the answers in (I) and (II) above.

  Date posted: September 9, 2019 .    Answers (1)

• A coin is placed at the bottom of a tall jar. The jar is filled with paraffin to a depth of 32.4 cm and the... (Solved)
  

  A coin is placed at the bottom of a tall jar. The jar is filled with paraffin to a depth of 32.4 cm and the coin is apparently seen displaced 9.9 cm from the bottom. Determine the refractive index of air with respect to paraffin.

  Date posted: September 6, 2019 .    Answers (1)

• A transformer has 200 turns in the primary coil and 1000 turns in the secondary coil. The primary coil is connected to an a.c source... (Solved)
  

  A transformer has 200 turns in the primary coil and 1000 turns in the secondary coil. The primary coil is connected to an a.c source producing 100 V and rated 500 W. The current delivered by the secondary circuit was found to be 0.95 A.
  (i) Determine the efficiency of this transformer.
  (ii) Explain why the efficiency is less than 100%.

  Date posted: September 6, 2019 .    Answers (1)

• A bar magnet is pushed into a coil as shown in the figure below. (Solved)
  

  A bar magnet is pushed into a coil as shown in the figure below.
  
  Explain what happens to the pointer of the galvanometer when the magnet is:
  (i) Moved into the coil rapidly?
  (ii) Remains stationary inside the coil?

  Date posted: September 6, 2019 .    Answers (1)

• An electric kettle is rated at 1.8 kW, 240 V. Explain the choice of the safest fuse for the kettle. (the available fuses are 5... (Solved)
  

  An electric kettle is rated at 1.8 kW, 240 V. Explain the choice of the safest fuse for the kettle. (the available fuses are 5 A, 10A, and 20 A)

  Date posted: September 6, 2019 .    Answers (1)

• The figure below shows a wave form.Determine the wavelength given that the speed of the wave is 400 m/s. (Solved)
  

  The figure below shows a wave form.Determine the wavelength given that the speed of the wave is 400 m/s.
  
  

  Date posted: September 6, 2019 .    Answers (1)

• The range of audible frequencies varies from 20 Hz to 20 kHz. If the speed of sound is 340 m/s, what is the corresponding range... (Solved)
  

  The range of audible frequencies varies from 20 Hz to 20 kHz. If the speed of sound is 340 m/s, what is the corresponding range of wavelength?

  Date posted: September 6, 2019 .    Answers (1)

• The chart below shows part of the electromagnetic spectrum. (Solved)
  

  The chart below shows part of the electromagnetic spectrum.
  
  (a) Identify the radiation marked A and C.
  (b) Give one application of the radiation marked B.

  Date posted: September 6, 2019 .    Answers (1)

• The figure below shows a steel bar to be magnetized. (Solved)
  

  The figure below shows a steel bar to be magnetized.
  
  Complete the circuit such that both poles P and Q acquire opposite polarity (North- south respectively).

  Date posted: September 6, 2019 .    Answers (1)

• An object of height 2 cm is placed 25 cm in front of a concave mirror. A real image is formed 75 cm from the... (Solved)
  

  An object of height 2 cm is placed 25 cm in front of a concave mirror. A real image is formed 75 cm from the mirror.Calculate the height of the image.

  Date posted: September 6, 2019 .    Answers (1)

• The figure below shows a ray of light incident on a plane mirror. (Solved)
  

  The figure below shows a ray of light incident on a plane mirror.
  
  (a) On the diagram, indicate the direction of the reflected ray.
  (b) Give a reason for the path shown above.

  Date posted: September 6, 2019 .    Answers (1)

• A certain mass of hydrogen gas occupies a volume of 1.6m³ at a pressure of 1.5x10⁵Pa and a temperature of 12⁰c. Determine the volume when... (Solved)
  

  A certain mass of hydrogen gas occupies a volume of 1.6m³ at a pressure of 1.5x10⁵Pa and a temperature of 12⁰c. Determine the volume when the temperature is 0⁰c at a pressure of 1.0x10³

  Date posted: September 6, 2019 .    Answers (1)

• A cork of volume 100cm³ is floating on water. If the density of the cork is 0.25 gcm^-3 and that of water is 1 gcm^-3; (a)... (Solved)
  

  A cork of volume 100cm³ is floating on water. If the density of the cork is 0.25 gcm^-3 and that of water is 1 gcm^-3;
  (a) Calculate the mass of the cork
  (b) Hence, find the upthrust force on the cork
  (c) What minimum force is required to immerse the cork completely
  (d) What is the effect on the upthrust force in a liquid when the temperature of the liquid is reduced?

  Date posted: September 6, 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 = 60g
  - mass of water + calorimeter = 145g
  - Final mass of calorimeter + water + condensed steam = 156g
  - Final temperature of the mixture = 48^oC
  [Specific heat capacity of water = 4200JKgˉ¹kˉ¹ and specific heat capacity of copper = 390JKgˉ¹kˉ¹
  Determine the;
  (i) mass of condensed steam.
  (ii) The heat gained by the water and calorimeter if the initial temperature of the calorimeter and water is 20ºC.
  (iii) Given that Lv is the specific latent heat of vaporization of steam, write an expression for the heat given out by steam.
  (iv) Determine the value of Lv above
  (v) State the assumption made in the above experiment

  Date posted: September 6, 2019 .    Answers (1)

• The diagram below shows a graph of force against extension for a certain spring. (Solved)
  

  The diagram below shows a graph of force against extension for a certain spring.
  
  (i) What is the spring constant of the spring?
  (ii) What force would cause two such springs placed side by side to stretch by 10cm

  Date posted: September 6, 2019 .    Answers (1)

• The height of a mountain is 1360m. The barometer reading at the base of the mountain is 74cmHg. Given that the densities of mercury and... (Solved)
  

  The height of a mountain is 1360m. The barometer reading at the base of the mountain is 74cmHg. Given that the densities of mercury and air are 13,600Kgm^-3 and 1.25Kgm^-3 respectively, determine the barometer reading at the top of the mountain.

  Date posted: September 6, 2019 .    Answers (1)