Course Content
Properties of Matter
OBJECTIVES By the end of this topic , the trainee should be able to: 1.Explain the three states of matter. 2.Explain phenomenon of surface tension. 3.Explain gas laws.
0/3
Introduction
States Of Matter
Gas Laws
Measurement
OBJECTIVES By the end of this topic , the trainee should be able to: 1.State the basic and derived quantities of measurements 2.Describe quantities of measurements 3.State the SI units of quantities of measurements and their sub-multipliers 4.Convert units from one to another
0/4
Introduction
Measurement of Length and Distance
  Measurement of Mass and weight
 Measurement of Volume and Density
Pressure
OBJECTIVES By the end of this topic , the trainee should be able to: 1.Define pressure 2.Determine pressure in solids and fluids 3.Explain the type of instruments used in measurement of pressure of gases 4.Explain transmission of presure in liquids
0/2
Introduction
Measuring Pressure
Force
OBJECTIVES By the end of this topic, the trainee should be able to: 1.Define force and its SI units 2.Explain types of force 3.Measure force 4.Work out calculations involving force 5.Explain Hooke’s law
0/3
Force
Friction Force
Centrifugal and Centripetal Force
Hooke’s Law
Hooke's Law  is a law named after 17th century British physicist Robert Hooke, who sought to demonstrate the relationship between the forces applied to a spring and its elasticity.
0/1
Hooke’s Law
Moments
OBJECTIVES By the end of this topic, the trainee should be able to: 1. Define moments of a force 2.Explain principles of moments 3.Explain statics , dynamics and kinematics
0/1
Moments
Velocity and Speed
OBJECTIVES By the end of this topic , the trainee should be able to : 1.Define speed and velocity 2.Explain types of motion 3.Determine Linear Determine Circular Motion
0/1
Velocity and Speed
Work and Power
OBJECTIVES By the end of this topic , the trainee should be able to: 1.Define work and power 2.Work out calculations involving work and power
0/1
Work and Power
Energy
OBJECTIVES By the end of this topic, the trainee should be able to: 1.Define energy 2.Explain forms of energy 3.Explain law of conservation of energy
0/1
Energy
Motion
OBJECTIVES By the end of this topic, the trainee should be able to: 1.Define motion 2.Explain causes of motion 3.Explain types of motion 4.Describe linear and circular motion
0/3
Introduction
Linear Motion 
Circular Motion
Newton’s Laws of Motion
OBJECTIVES By the end of this topic, the trainee should be able to: 1.State Newton’s laws of motion 2.Explain relationships between mass and inertia 3.Explain significance of Newton’s laws of motion
0/1
Newton’s Laws of Motion
Heat and Heat Transfer
OBJECTIVES By the end of this topic, the trainee should be able to 1.Define temperature and heat 2.Describe instruments used to measure temperature 3.Explain modes of heat transfer 4.Explain factors that influence heat transfer 5.Explain heat capacity, specific heat capacity and specific latent heat of substances 6. Work out calorimetric calculations
0/5
Introduction
Instruments Used For Measuring Temperature  
Heat Transfer
Measuring The Quantity Of Heat
Heat and Changes of State
Light
OBJECTIVES By the end of this topic , the trainee should be able to: 1.Define light and its properties 2.Explain types of mirrors and lenses 3.Explain reflection and refraction of light 4. Explain the lens formulae
0/10
Introduction
Mirrors
Reflection 
Mirror Equation
Image Formation By Convex Mirror
Refraction Of Light
 Refractive index
Thin Lenses
The lens formula
 Uses of lenses on optical devices
WAVES
OBJECTIVES By the end of this topic , the trainee should be able to : 1. Define waves 2.Explain types of waves 3.Explain characteristics and properties of waves 4.Explain rectilinear propagation of waves 5.Describe refraction of waves 6.Describe sound and sound waves
0/6
Introduction
Electromagnetic Wave
Electromagnetic Wave
Properties of Waves
Rectilinear Propagation Of Waves
Sound and Sound Waves
Electrostatics
OBJECTIVES By the end of this topic , the trainee should be able to: 1.Define electrostatics 2. Describe the working of electroscopes 3.Describe different methods of charging a body 4.Explain electric fields 5.Describe charge distribution on conductors’ surface 6. Describe capacitors and capacitance
0/5
Introduction
Gold Leaf Electroscope
Electric Fields
Charge Distribution on Conductors’ Surface
Capacitors And Capacitance
Magnetism and Electromagnetism
OBJECTIVES By the end of this topic, the trainee should be able to: 1.Define magnetism 2.Identify magnetic and non- magnetic materials 3.Explain properties of magnets 4.Describe magnetic field patterns 5.Describe making magnets 6.Explain domain theory of magnets 7.Describe magnetic effect of an electric current. 8. Describe electromagnets and electromagnetism 9.Describe electromagnetic induction
0/6
Introduction
Magnetic Field Patterns.
Making Magnets
Magnetic Effect of An Electric Current.
Electromagnetism 
Electromagnetic Induction
Current Electricity
CURRENT ELECTRICITY OBJECTIVES By the end of this topic, the trainer should be able to: 1. Define current and electricity 2.Electric potential difference 3.Explain use of a meters, voltmeters and resistors 4.Explain ohm’s law 5. Explain Electromotive force and internal resistance 6.Describe production of electric current 7.Describe simple cells, Leclanche’ cell, dry cells and lea-acid accumulators 8.Describe mains electricity 9.Describe domestic wiring
0/6
Introduction
Electric Potential Difference And Electric Current
Resistors and Resistance
Production Of Electric Current:
Heating Effect Of An Electric Current
Mains Electricity
Electromagnetic Spectrum
OBJECTIVES By the end of this topic , the trainee should be able to: 1.Define magnetic spectrum 2. Explain properties of electromagnetic waves 3. Describe applications of electromagnetic radiation
0/2
Introduction
Properties and Application of Electromagnetic Waves
Radioactivity
OBJECTIVES By the end of this topic, the trainee should be able to: 1. Define radioactivity 2.Classify radiations 3.Explain the properties of radiation materials 4.Describe nuclear fission and nuclear fusion 5.Describe methods for detecting nuclear radiation 6.Describe activity and half-life of elements 7. Discuss hazards of radioactivity and their precautions 8. Outline the applications of radioactivity
0/4
Introduction
Nuclear Fission
Activity and Half-Life Of Elements
Applications Of Radioactivity
Cathode and X-Rays
OBJECTIVES By the end of this topic, the trainee should be able to: 1. Define cathode and X- rays 2.Explain production of cathode and X- ray 3.Explain properties of cathode and X- ray 4.Describe cathode ray oscilloscope (CRO) 5. Describe the applications of Cathode and X-rays
0/2
Cathode Rays
X-Rays
Physics Techniques For Science Laboratory Technicians
About Lesson

Views: 77

Measuring Pressure

  1. Simple mercury barometer– it is constructed using a thick walled glass tube of length 1 m and is closed at one end. Mercury is added into the tube then inverted and dipped into a dish containing more mercury. The space above the mercury column is called torricellian vacuum.

The height ‘h’ (if it is at sea level) would be found to be 760 mm.

Atmospheric pressure can be calculated as,

  • P = ρ g h
  • where ρ (mercury)- 1.36 × 104 kg/m3, g- 9.81 N/kg, h- 0.76 m.
  • Then P = (1.36 × 104) × 9.81 × 0.76
  •  = 1.014 × 105 Pa.

NOTE- this is the standard atmospheric pressure, sometimes called one atmosphere. It is approximately one bar.  

  1. Fortin barometer–this is a more accurate mercury barometer. The adjusting screw is adjusted first to touch the mercury level in the leather bag.

2. Aneroid barometer– increase in pressure causes the box to contract, the movements are magnified by the system of levers and is transmitted to the pointer by the fine chain and this causes the pointer to move.

The scale is suitably calibrated to read pressure. Since pressure falls or rises as altitude falls or rises, the pointer can also be calibrated to read altitude.

3.Bourdon gauge– it is also called gauge pressure and is used in gas cylinders. When air is blown into the rubber tube, the curved metal tube tries to straighten out and this causes movement which is transmitted by levers and gears attached to a pointer. This gauge can measure both gas and liquid pressure.

  •  Examples

The height of the mercury column in a barometer is found to be 67.0 cm at a certain place.

What would be the height of a water barometer at the same place? (densities of mercury – 1.36 × 104 kg/m3 and water- 1.0 × 103 kg/m3).

 Solution

 Let the pressure due to water be h1 ρ1 g1 and that of water be h ρ g. Then h1 ρ1 g1 = h ρ g. Hence h1 = (6.7 × 10-1) × (1.36 × 104) / 1.0 × 103 

= 911.2 cm or 9.11 m.

 Application Of Pressure In Gases And Liquids.

 1. Rubber sucker– this is a shallow rubber cap. Before use it is moistened to get a good seal then pressed firmly on a smooth surface so that the air inside is pushed out. The atmospheric pressure will then hold it firmly against the surface as shown below.

They are used by printing machines to lift papers, lifting glass panes, heavy metal sheets etc.

 2. Drinking straw– when a liquid is drawn using a straw air is sucked through the straw to the lungs. This leaves the space in the straw partially evacuated. The atmospheric pressure pushing down the liquid in the container becomes greater than the pressure inside the straw and this forces the liquid into your mouth.

3. The syringe– they work in the principle as the straw. They are used by the doctors in hospitals for giving injections.

 4. Bicycle pump– it uses two valves, one in the pump (greasy leather) and the other in the tire. When the handle is pushed in, the pressure inside the barrel becomes greater than the one in the tire and this pushes air inside.

The valve in the tire is made such that air is locked inside once pumped.

 ·  

5. The siphon– it is used to empty tanks which may not be easy to empty by pouring their contents out.

The tubing must be lowered below the base of the tank.

The liquid flows out due to pressure difference caused by the difference in height ( h ρ g).

  •  ·

Transmission of pressure in liquids and gases.

  • Pressure is equally distributed in a fluid and equally transmitted as shown in  the following illustrations ,
  1. Hydraulic brake system– the master cylinder transmits pressure to the four slave cylinders on each wheel.

 

 The cylinders contain brake fluid. This fluid is used because liquids are almost incompressible.

 When force is applied in the pedal the resulting pressure in the master cylinder is transmitted to the slave cylinders.

This forces the piston to open the brake shoes which then pushes the brake lining against the drum.

 This force the rotation of the wheel to slow down. It is important to note that pressure is equally distributed in all wheels so that the car doesn’t pull or veer to one side.

b) Hydraulic press– it consists of two pistons with different cross -sectional areas. Since pressure is transmitted equally in fluids, when force is applied in one piston it is transmitted to the other piston.

The smaller piston is called the force while the bigger piston is called the load.

 They are used to lift heavy loads in industries, bending metals and sheets etc.

 ·

Examples

  1. The area of the smaller piston of a hydraulic press is 0.01 m2 and that of the bigger piston is 0.5 m2. If the force applied to the smaller piston is 2 N, what force is transmitted to the larger piston?

 Solution

Pressure = force / area – hence P = 2 / 0.01 = 200 Pa.

Force = Pressure × Area = 200 × 0.5 = 100 N.

2. The master cylinder piston in a car braking system has a diameter of 2.0 cm.The effective area of the brake pads on each of the four wheels is 30 cm2. The driver exerts a force of 500 n on the brake pedal. Calculate.

  1. a) The pressure in the master cylinder.
  2. b) The total braking force in the car.

Solution

a) Area of the master cylinder – π r2 = 3.14 cm2

  • Pressure = force /area = 500 / 3.14 × 10-4
  •  = 1.59 × 106 N/m2

b) Area of brake pads = (30 × 4) cm2. Since pressure in the wheel cylinder is the same as in the master cylinder)2

F = Pressure × Area = (1.59 × 106) × (120 × 10-4)

 = 1.91 × 104 N.


Join the conversation
Previous
Next

You cannot copy content of this page