Sunday, 26 March 2017

Physics: Introduction to radioactivity,types and properties.

radioactivity

Radioactivity

It is a spontaneous emission of radiation from a substance usually an unstable   .This process is also known as nuclear or radioactive decay). In the year 1896, Henri Becquerel a French scientist working with phosphorescent materials discovered that a uranium compound placed on a photographic plate which was covered with light black paper causing the plate to be exposed by blackening the pate itself. This implied that some sort of radiation was coming from the uranium which could pass through. The material was radioactive given-off radiation. Other scientists that researched on radioactivity were;v This radioactivity was spontaneous with the radiation being omitted without anything causing it apparently.

Types of radioactivity

From several experiments that have been carried out, it has shown that there are three different types of radioactive emission called;
 Alpha particles ; whose emission is easily stopped by paper or thick card
 Beta particles ; whose emission is easily stopped by aluminium sheet of different thickness and are negatively charged.
Gamma particles ; whose emission is easily stopped by thick sheet of lead.

types of radioactivity


Properties of alpha particles


      1)  Alpha rays are deflected by magnetic field.  
      2)      The direction of deflection of alpha rays shows that they are positively charged
      3)      They are relatively massive and so have more momentum and tend to continue in their direction of travel.
      4)      Alpha particles are absorbed by paper and air and are easily stopped aluminium thin sheet.
      5)      They have little penetrating power, travelling no more than 5cm. Being large, it is soon stopped by air molecules.
      6)      They are capable of stripping electrons from their atoms because alpha particles have comparatively large mass and momentum.


Properties of beta particles

     1)      There are also deflected by magnetic field but in the opposite direction to alpha particles.
     2)      The direction of deflection of beta rays shows that they are negatively charged with –e .
     3)      They are relatively light and as a result easily deflected.
     4)      They are deflected by different amount showing that they have varying speed..
     5)      They have good penetrating power of about 1 metre.
     6)      They can penetrate a few millimetre of aluminium.
     7)      They produce less ionisation in air than alpha particles.

Properties of gamma rays

    1)      They are electromagnetic waves similar to light wave but of very short wavelength.
    2)      They are electrically uncharged since they are not deflected by a magnetic field.
    3)      They are highly penetrative compared to the other two types and can only be stopped by thick lead blocks.
   4)      They have high penetrating power compared to the other two types.
   5)      They have much less ionisation than alpha rays.

Sunday, 12 March 2017

Physics: Thermal, linear, area and cubic expansivity

Thermal expansivity


Expansivity

 This is defined as amount a material expands or contracts per unit length, per-degree change in temperature.
The addition of heat will usually cause expansion of the body. during expansion, the dimension of the body increases.

Friday, 10 March 2017

General maintenance of film rollers of a machine





Maintenance of film rollers.
This part of an industrial machine contain a certain number of rollers rotating at different speeds. If a film passes through these rollers, it would be stretched out length-wise or width-wise depend on its specification and function. In most cases, the occurs at high temperature for smooth operations and the bearings and materials used must be able to withstand the set temperatures.

Learn how to maintain the film rollers of your equipment and keep the in excellent condition. This part of an equipment is found in fill/seal packaging machinery used in the paper or plastic industry.
    Be sure to also put safety first in any maintenance carried out.


Importance


  • To maintain standards
  • To minimise waste
  • For easy sealing
  • To stretch out fibres




                 READ ALSO: 






                                   Safety Check:      
                          
           (1) Use vacuum cleaner to clean.               
 (2)  Wear all your protective wears (eye goggle, hand gloves, nose mask, an overall )


 Tools
:
Eye Goggle, Nose Mask


 Task
:
Inspect/Clean The Film Rollers
.


 Why:
Ensure Free Movement Of The Film Rollers.
Procedures
1. Put on all required recommended professional and protective equips.
  1. Check for buildup on the Film Rollers.
3. Check if the Films are moving Freely and Properly without friction.
4. Check the rollers have any dent on its surface.
5. If there's build up on the Film Rollers Use clean rag to Thoroughly Clean The Film Rollers.

READ ALSO: 
·         Oil level check
·         Oil consistency check

Conclusion
 The is basically just a general means of maintaining machine film rollers. The are numerous machine design, dimensions, materials of construction etc. In most cases, these rollers may be made of metal alloy, because of its Strength and ability to withstand high temperatures, but some other manufacture may decide to use other materials that best fits their design. Remember to always read the machine manuals.


Wednesday, 8 March 2017

Introduction to Energy, conservational law, Mechanical energy; potential and kinetic energy, examples






Energy




Energy can be defined as the capacity to perform work. Thus, the unit of energy is the same as that of work. That is, the s.i unit of energy is joule. We have various types of energy; kinetic energy (Such as, the energy from a moving car or a falling stone), chemical energy, heat energy, electrical energy,  light energy, light energy, sound energy, nuclear energy.

Conservation law

 All the forms of energy listed above can be changed from on form to another by means of suitable machine or apparatus, for example; the energy in the nucleus of atoms produces heat energy, which in turn can be used to generate electrical energy. The mechanical energy that moves a car comes from heat  energy derived from the volume of fuel which is stored as chemical energy.


The principle of conservation of energy states that although energy can be changed from form to another, the total energy of given system remains unchanged i.e energy can neither be created nor destroyed during transformation.

Mechanical Energy

A body can possess mechanical energy or have the ability to work for two reasons either by virtue of its position or because of its motion. The two kinds of energy are called kinetic energy and potential energy respectively.

Kinetic energy

  It is energy a body possesses because it is in motion.
Mathematical formula, 
   KE =   1/2 mv2       Where m = mass, v = velocity.

Other forms of kinetic Energy:


  1. Electrical Energy: This is the movement of electrons. Examples: lightning and electricity. 
  2. Motion: This is the movement of substances from one place to another. 
  3. Thermal Energy: This is the movement and vibration of atoms and molecules within a substance. For example, geothermal energy. 
  4. Radiant Energy: This is electromagnetic energy that travels in transverse waves. Examples: X-rays, gamma rays, Alpha rays and so on. 
  5. Sounds: This is the movement of energy through substances in longitudinal waves. 




Potential energy

   It is the energy a body possesses because of its position. A body of mass (m) raising to a height (h) above the ground is said to possess potential energy.
   Mathematical formula, 
   KE = mgh       Where m = mass, g = acceleration due to gravity, h = distance.

Other forms of kinetic Energy:


  1. Chemical Energy: This is the energy stored in bonds of atoms and molecules. Examples: petroleum, natural gas, coal and so on. 
  2. Gravitational Energy: This is the energy of place and position. 
  3. Nuclear Energy: This is the energy stored in the nucleus of an atom. For example, the nucleus of uranium atom.

 

Power: This is defined as the rate of doing work or the rate of transfer of energy.
Average power = (work done or energy extended)/(time taken)
Power = (mgh)/t
     The S.I unit of power is watt (W),former unit of power was horse-power.


Examples

  1) A boy of mass 30kg is running with a speed of 4 m/s. What is his kinetic energy?
Solution
KE =   1/2mv2
M = 30kg, v = 4m/s
KE = 240J

 2) A bullet of mass 4g is moving with a speed of 216 km/hr. Calculate its kinetic energy.

Solution

M = 0.04 kg
V = 216km/hr
1hr = 60min
1000m = 1km
V =  60m/s
KE =72J

3)  Calculate the power of a pump which lifts 500kg of water through a vertical height of 4m in 5 seconds.

Solution

P = mgh/t
m = 500kg
h=4m
g=10m/S2
Power = 4000J

 4) A bullet of mass 0.05kg has a speed of 400m/s. What is the kinetic energy, if it hits a wall of which of the average resistance is 10000N. Calculate the distance penetrated by the bullet.

Solution

   KE =   1/2mv2      
KE = 0.5 x 0.05 x 400 x 400
KE = 4000J
Energy =work done = Force x distance
4000J = 10000 x d
Distance penetrated by the bullet = 0.4m