1. Force, Work, Power and Energy
(i) Turning forces concept; moment of a force; forces in equilibrium; centre of gravity; [discussions using simple examples and simple numerical problems].
Elementary introduction of translational and rotational motions; moment (turning effect) of a force, also called torque and its cgs and SI units; common examples - door, steering wheel, bicycle pedal, etc.; clockwise and anti-clockwise moments; conditions for a body to be in equilibrium (translational and rotational); principle of moment and its verification using a metre rule suspended by two spring balances with slotted weights hanging from it; simple numerical problems; Centre of gravity (qualitative only) with examples of some regular bodies and irregular lamina.
(ii) Uniform circular motion.
As an example of constant speed, though acceleration (force) is present. Differences between centrifugal and centripetal force.
(iii) Work, energy, power and their relation with force.
Definition of work. W = FS cosθ; special cases of θ = 0°, 90°. W = mgh. Definition of energy, energy as work done. Various units of work and energy and their relation with SI units [erg, calorie, kW h and eV]. Definition of Power, P = W/t; SI and cgs units; other units, kilowatt (kW), megawatt (MW) and gigawatt (GW); and horsepower (1hp = 746W) [Simple numerical problems on work, power and energy].
(iv) Different types of energy (e.g., chemical energy, Mechanical energy, heat energy, electrical energy, nuclear energy, sound energy, light energy).
Mechanical energy: potential energy U = mgh (derivation included) gravitational PE, examples; kinetic energy K = ½mv² (derivation included); forms of kinetic energy: translational, rotational and vibrational - only simple examples. [Numerical problems on K and U only in case of translational motion]; qualitative discussions of electrical, chemical, heat, nuclear, light and sound energy, conversion from one form to another; common examples.
(v) Machines as force multipliers; load, effort, mechanical advantage, velocity ratio and efficiency; simple treatment of levers, pulley systems showing the utility of each type of machine.
Functions and uses of simple machines: Terms- effort E, load L, mechanical advantage MA = L/E, velocity ratio VR = VE/VL = dE/dL, input (Wi), output (Wo), efficiency (η), relation between η and MA (derivation included); for all practical machines η <1; MA < VR. Lever: principle. First, second and third class of levers; examples: MA and VR in each case. Examples of each of these classes of levers as also found in the human body. Pulley system: single fixed, single movable, block and tackle; MA, VR and η in each case.
(vi) Principle of Conservation of energy.
Statement of the principle of conservation of energy; theoretical verification that U + K = constant for a freely falling body. Application of this law to simple pendulum (qualitative only); [simple numerical problems].