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In vectors 2+2 is not equal to 4. It could be anything between from -4 to +4 depending on the angle between the two vectors.
Taking the components of a vector along X and Y axes has the advantage of that all the X components can be added together and the same with Y components.Then the resultant is obtained.
Vector product of 2 vectors means the product of the two vectors is a vector. A scalar product of two vectors is a scalar. It is also a product of 2 vectors.The scalar product of displacement and force vectors gives work done. If the force also have a perpendicular component , then the cross product between them yields torque .Just as a force causes a displacement a torque causes rotation.This is the rate of change of angular momentum.
A vector product has a direction which is perpendicular to the plane containing both r and F. In scalar product ,the vectors as well as product are in same plane.
A force is defined as a rate of change of momentum. A body of constant mass changes it if a force is applied.
If the mass is constant ,a constant force will produce a constant acceleration.
If the mass is decreasing, a constant force will increase the velocity .one gets positiveacceleration.
If the mass goes on incresing the application of same force cannot maintain the velocity. Deceleration will be present.
Inertia is an index of resistance of body to change its state.Its qualitative value is mass .Greater the mass greater inertia and vice versa .
When two different masses are freely falling from the same height above the surface of the earth ,their acceleration is the same .
The forces acting on them will be different.Greater the mass greater the force.
The time taken will be the same.
The work done by the bigger mass will be greater than the smaller mass .
For the same body the rate of fall in the first second will be different from rate in the last second. It is in the ratio (1)2 : (2)2:(3)2:....... for the first,second,third second resp.....
The force acting on the same body of mass m can be different as the distance of the body from the surface increases .
mass is conserved. Law of conservation of mass is usually observed in classical physics .
Conservation of momentum is observed in elastic as well as inelastic collissions.
conservation of energy is valid in elastic but invalid in inelastic collissions.
In circular motion ,the torque causes the initial rotation , when it is removed ,the motion is uniform and angular velocity is constant . the body continues to rotate because of conservation of angular momentum.
The centripetal force is balanced by centrifugal force .There is no net acceleration. the velocity is tangential.
Moment of inertia replaces mass in rotational motion.
Inaccelerated motion tangential as well as angular acceleration are produced .

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