Important Short Questions and Answers: Basics and Statics of Particles

1. Define force?

Force is a physical quantity that changes or tires to change the state of rest or of uniform motion of an object

2.  Differenciate between particles and rigid body?

Particle is a body which has mass but no dimension where as rigid body as both mass and dimensions.Particle can have only translational motion where as rigid body can have translational as well as rotational motion.

3.  State newton’s first law of motion?

Everybody tries to be in it’s state of rest or of uniform motion along a straight line unless it’s acted upon by an external unbalanced force .

4.  State newton’s second law of motion?

The rate of change of momentum of a body is directly proportional to the applied force and takes place in the direction of the force .

5.  State newton’s third law of motion?

Every action has an equal and opposite reaction .

6.  State law of parallelogram of vectors?

If two vectors are represented in magnitude and direction by two adjacent sides of a parallelogram,their resultant is represented in magnitude and direction by the diagonal of the parallelogram drawn from the common point.

7.  State the principle of transmissibility of force with simple sketch?

According to principle of transmissibility of force,the force can be transmitted from one point to another on it is line of action without causing by any change in the motion of the object. EG:force F can be transmitted from A to B.

8.  Define unit vector?

A vector having magnitude one unit is known as a unit vector .

9.                 Define the following terms?

(a)coplanar forces (b)concurrent forces

(a)If all forces act in one plane,they are known as coplanar forces.

(b)If lines of action of all forces intersected at a single point,the forces are known as concurrent forces.

10.            Defferentiate between collinear and concurrent forces?

Collinear forces act along the same line where as concurrent forces have lines of action intersecting at one point.

11     .Define resultant of coplanar concurrent force system?

A system of coplanar concurrent forces can be reduced to a single force which is known as resultant force.

12. what is the difference between a resultant force and equilibrant force?

Resultant force makes the object move whereas equilibrant force keeps it in equilibrium.

13.            state triangle law of forces?

If two forces are represented in magnitude and direction by two sides of a triangle taken in order,their resultant is represented in magnitude and direction by the third side of the triangle drawn from starting point of first force to end point of the second force.

14.            State parallelogram law of forces?

If two forces are represented in magnitude and direction by two adjacent sides of a parallelogram,their resultant is represented in magnitude and direction by the diagonal of the parallelogram drawn from the common point.

15.            Statelami’s theorem?

If three concurrent forces are in equilibrium,magnitude of any force is proportional to the sine of angle between the other two forces.

16. State the necessary and sufficient condition for static equilibrium of a particle in two dimensions?

For static equilibrium of a particle in two dimensions,

i)The algebraic sum of horizontal components of all forces acting the particle must be zero.

ii) The algebraic sum of vertical components of all forces acting the particle must be zero.

17 .State triangle law of equilibrium?

If three forces acting on a particle are represented by the three sides of a triangle in magnitude and direction when taken in order,the particle will remain in equilibrium.

18.What is a free body diagram?

A force system,in a plane,in which the lines of action all forces intersect at a single point is called coplanar concurrent force system.

1.Distinguish the following system of forces with a suitable sketch. a) Coplanar b) Collinear 2.Define Kinetics and Kinematics

3.State Lami’s theorem with a sketch.

4.State parallelogram law and triangle law of forces. 5.What are fundamental and derived units? Give examples 6.Distiguish between units and dimensions. Give examples. 7.Define principle of transmissibility.

8.A force vector F= 700i + 1500j is applied to a bolt. Determine the magnitude of the force and angle it forms with the horizontal.

9.A force of magnitude 50 KN is acting along the line joining A(2,0,6) and B(3,-2,0)m. Write the vector form of the force.

10.Two forces of magnitude 50 KN and 80 KN are acting on a particle, such that the angle between the two is 135°. If both the force are acting away from the particle, calculate the resultant and find its direction.

11.A 100N force acts at the origin in a direction defined by the angles θx = 75° and θy = 45°.Determine θz and the component of the force in the Z-direction.

12.Write the equations of equilibrium of a coplanar system of forces. 13.Differentiate between ‘Resultant’ and ‘Equilibrant’

14.Find the resultant of an 800N force acting towards eastern direction and a 500N force acting towards north eastern direction.

15.Find the magnitude of the two forces such that if they act at right angles, their resultant isÖ10 N. But if they act at 60° their resultant is Ö13 N.