8 Theory of Machines
We have discussed in the previous Chapter, that the
subject of Theory of Machines deals with the motion and
forces acting on the parts (or links) of a machine. In this chap-
ter, we shall first discuss the kinematics of motion i.e. the
relative motion of bodies without consideration of the forces
causing the motion. In other words, kinematics deal with the
geometry of motion and concepts like displacement, velocity
and acceleration considered as functions of time.
When the motion of a body is confined to only one
plane, the motion is said to be plane motion. The plane mo-
tion may be either rectilinear or curvilinear.
It is the simplest type of motion and is along a straight
line path. Such a motion is also known as translatory motion.
2.4. Curvilinear Motion
It is the motion along a curved path. Such a motion,
when confined to one plane, is called plane curvilinear
When all the particles of a body travel in concentric
circular paths of constant radii (about the axis of rotation
perpendicular to the plane of motion) such as a pulley rotating
2. Plane Motion.
3. Rectilinear Motion.
4. Curvilinear Motion.
5. Linear Displacement.
6. Linear Velocity.
7. Linear Acceleration.
8. Equations of Linear Motion.
9. Graphical Representation of
Displacement with respect to
10. Graphical Representation of
Velocity with respect to Time.
11. Graphical Representation of
Acceleration with respect to
12. Angular Displacement.
13. Representation of Angular
Displacement by a Vector.
14. Angular Velocity.
15. Angular Acceleration.
16. Equations of Angular Motion.
17. Relation Between Linear
Motion and Angular Motion.
18. Relation Between Linear and
Angular Quantities of
19. Acceleration of a Particle
along a Circular Path.
Chapter 2 : Kinematics of Motion 9
about a fixed shaft or a shaft rotating about its
own axis, then the motion is said to be a plane