AERONAUTICAL LECTURING NOTES

What is machine? A machine is any device which reduces human effort by using mechanical parts and concepts. In what are the ways we use machines? Give examples too. 1.     Machines are used to transform energy- Generator 2.     Machines are used to transfer energy from one place to other – Crank shaft 3.     Machines are used to multiply the energy- Pulley 4.    Machines can be used to multiply speed- Bicycle 5.     Machines can be used to change the direction of a force – Flag hoist What are the simple machines available? 1.     Lever 2.     Pulley 3.     wheel and axle 4.     inclined plane 5.     Screw 6.    Gear

Define force The most commonly used type of input in mechanical system is force and it is the reason for moment, torque, stress to exist. When a force acts over a body; it gets imbalanced ; and moves in the direction of applied force. Define Work Work is the output made from the input; force. Mathematically Work = Force x Distance (N-m or Joule) Define torque Torque is described as force acting along a distance (Perpendicular distance). Torque creates twisting and makes rotation. Torque = Force × distance Define friction When a body moves or tends to move over other body, a force appears between the objects of interest. This force is called friction. Friction acts opposite to the direction of motion. Mathematically F  =   µ X R F- Friction; µ- Coefficient of friction; R- Normal force acting between surfaces Define power Power = (Force x Distance) / time      ((N-m)/s) Or  Watts