** **__WORK, ENERGY AND POWER__

**Work**
= F s Cos q where
q is the angle between force (F) and
displacement(s).

**Translational kinetic energy** of a body of mass
‘m’ and velocity ’v’ is

K.E = ½ mv^{2}

**Rotational kinetic energy** of
a body of moment of inertia ‘I’ and angular velocity _{} is

K.E_{rot}=
½ I_{}^{2}

**Gravitational Potential energy** = mgh, where h is the height with respect to some

reference point

**Elastic Potential energy of a spring**** **=
½ kx2, where k is the spring constant,

x
is displacement from equilibrium
position

**Power**** **is the work done per unit time.

P = _{}

**Instantaneous Power**
= _{} = **F**.**v**

**
**__GRAVITATION__

**Newton****’s law of Gravitation**
If m_{1 }& m_{2} are the masses separated by distance r,
then the force between them is

F =_{}, G is universal Gravitational constant = 6.67 x 10^{-11}
Nm^{2}/kg^{2}

**Acceleration due to gravity** at a distance r
from the centre of a planet of mass M is

g = _{}^{}

^{ }

**Gravitational Potential** at a distance r in the gravitational
field of mass M is

V = _{}

**Orbital velocity** of a satellite at a height h from a
planet of mass M and radius R is

v_{o}= _{}

**Escape velocity** of a body from the surface of a planet
of radius R and mass M is

ve= _{}