Applied Mechanics (Part-2) (General Engineering) (SSC JE)

A concurrent force system is one in which the lines of action of all the forces intersect at a common point O then the force system produces no moment about the common point.

Parallelogram law of forces–It states that if two forces acting simultaneously at a point be represented in magnitude and direction by two adjacent sides of parallelogram, their resultant may be represented in magnitude and direction by diagonal of the parallelogram which passes through their points of intersection.

1. Kinetic frictional force–Frictional force that is developed when motion or sliding takes places at the contacting surface.

2. Static friction force–When motion is not takes place.

3. Limiting friction force–When motion or sliding is about to start then the maximum friction force is known as limiting friction.

According to Newton's first law of motion, a body cannot change its state of rest or of uniform motion along a straight line unless an external force acts on it.

• It means that the natural tendency of the material body to remain continue in the state of rest or that of uniform motion, which is termed as inertia. Thus, Newton's first law is the law of inertia.

Inelastic collision–An inelastic collision is one in which the total kinetic energy of the system is not the same before and after the collision (even through the momentum of the system is conserved).
1. Before the collision the particles move separately–
2. After the collision the particles move together–
3. When the object stick together after they collide, as happens when a meteorite collides with the earth, the collision is called perfectly inelastic.
4. When the colliding objects do not stick together but some kinetic energy is transformed or transferred away the collision is called inelastic.

The product of mass and velocity is called momentum.
P = mv
where, P = momentum, m = mass
v = velocity