## Pages

### Uniform Circular Motion,Friction And Frame Of refrence

Uniform Circular Motion
-A body moving with constant speed on the circle
-Acceleration is Directed towards centre
a=v2/r

Where v is the speed and r is the radius of the circle

-Centrepetal force is required to move the body in the circle
F=mv2/r

Friction:

Frictional force acts between the bodies whenever there is a relative motion between them.
When bodies do the slip ,frictional force is called static frictional force and when the bodies does not slip ,it is called kinetic frictional force.

Kinetic Frictional force:-When bodies slip over each other

f=μkN

Where N is the normal contact force between the surface
And μk is the coefficent of kinetic Friction

Direction of frictional force is such that relative slipping is opposed by the friction

Static Frictional force:

-Frictional force can also act even if there is no relative motion.Such force is called static Frictional force
-Maximum Statix friction that a body can exert on other body in contact with it is called limiting Friction.
fmaxsN

Where
N is the normal contact force between the surface
And μs is the coefficent of static Friction
fmax is the maximum possible force of static Friction

Some Imp points
1. μs > μk
2 Angle of friction tanλ=μs

Frame Of refrence:

Inertial Frame Of refrence:

-Inertial frame of refrences are objects which are at rest or moving at constant Velocity
-Exmaple:A person standing in a train moving at constant velocity
-Newtons law are valid

Non Inertial Frame Of refrence:-Inertial frame of refrences are objects which are accelerated
-Exmaple: A person standing in a train moving with increasing speed.
-Newtons law are not valid.

To apply newtons law ,pseudo force has to be introduced in the equation whose value will be
F=-ma

where a is the accelration of the non inertial frame of refrence