Mass as Inertia of the linear motion

There is a resistance in changing of moving stage for any moving object in case of either slow down the speed (velocity) or increasing the velocity or changing the direction of the motion. When you travel in a bus, your speed is equal to the speed of the bus. But imagine a time when the bus suddenly braked and stopped. Your speed will be the same as before and you will be thrown forward. Suppose this is due to a reluctance to change the existing speed. The more mass you have, the more force you will need to stop throwing forward.

As the mass of a car increases, more power is needed to move it. Thus it is clear that the state depends on its mass.



* The mass of an object does not depend on its location. It takes a definite value.

* The mass measured using inertia is called the inertial mass.

* Mass can be measured accurately from outside of gravity as gravity does not affect the inertial mass

In a gravitational field, the mass measured using a scale is the gravitational mass.

New Image
For example, the speed of an airplane running on a runway to take off increases relative to a point on Earth.

For example, the speed of an airplane running on a runway to take off increases relative to a point on Earth.

But the speed of the passenger relative to the aircraft remains stationary. Therefore the plane relative to the passenger is a stationary frame. This is called an inertial recommendation framework.

Position is measured relative to any fixed frame. But since there are no such static frames, relatively stationary frames are considered inertial frames.

Friction

 Friction force

 When there is a relative motion between two surfaces that are in contact with each other, or when there is such a temptation, the force acting on it against the contact surface is the force of friction

When a force p is applied to the mass m on the rough surface, gradually increasing from zero to zero, the friction force F is applied to the mass by the rough surface. To some extent the magnitude of F is equal to the magnitude of P. That is, the mass remains stationary because the total force is zero up to that limit.

In this case the active friction force is the static friction force. As the magnitude of F gradually increases, the value of F is maximal at one point

  At this point the object is in equilibrium very close to moving

 This state is called the limiting equilibrium state.

In this case the maximum frictional force exerted on the object is called F maximum and it is called the limiting friction force F limit.

Slightly increasing the value of P by or slightly above this maximum friction force causes the object to start moving.

Where M(mu) is the coefficient of friction between the rough surface and the object

                                                  

Thus   M (Mu) has no units

The magnitude of the limiting friction force does not depend on the rough surface and the area of ​​the contact object.

As the force on the smooth surface is gradually increased from zero to a plane parallel to the plane, the mass begins to move along the plane, as the smooth surface does not exert any frictional force against the motion.

Causes for friction

Major causes for friction are considered as intermolecular attraction- like electro-static forces of particles between two surfaces  and magnetic forces between them. we have to goto the particle level to identify them.

Example Question

Moment of a force Or Torque

 Moment of a force measures the ability of an object to rotate in a plane perpendicular to its axis under an external force

Force = Force * The force of action from the axis of rotation the vertical distance to the line

units of moment is Nm

The direction of the moment of a force is obtained by the right hand  law

When the fingers of the right hand are extended and directed in the direction in which an object is to be rotated by the action of the thumb force other than the thumb, the direction of force is obtained from the direction of the thumb.

Force systems

Resultant force

The total physical force exerted by a force system is single force  make same effect as the system.

 Parallelogram Law of adding 2 forces

When two forces are geometrically represented by two adjacent sides in parallelogram in terms of magnitude and direction, the sum of the two forces is obtained by the magnitude and direction of the diagonal of the parallelogram along the vertice where the two forces meet.

Let magnitude be the angle P with each of the magnitudes P and Q, the magnitude R of the sum of the two oblique vectors, and the angle a formed with the force P, the magnitude of the symmetry.

Draw the CL perpendicular to the extended AB base

From the ACL triangle

AC² = AL² + LC²

R² = (P + Q cosθ )²+(Qsinθ)²

R²=P²+2PQcosθ+Q²cos²θ+Q²sinθ

R²=P²+2PQcosθ+Q²(cosθ²+sinθ²)