Tim and Benny was analyzing the
following graph of motion of an
object, Tim says the object is
executing rectilinear motion, and
Benny says, no, it's not sure.
According to you who is right?
Explain.
Answers
1. When is an object said to be in motion?
An object is said to be in motion if its position changes with time
2. What is rectilinear motion?
The motion of an object along a straight line is known as rectilinear motion
3. What is kinematics?
Kinematics deals with the study of motion of bodies without considering the causes of
motion.
4. What is required to specify the position of an object?
To specify the position of an object, a reference point called origin is required.
5. What is meant by path length?
The total distance traversed by an object is called path length.
6. What is displacement?
The change of position in a particular direction or the distance between the initial and
final position of the object is called displacement.
7. What is meant by uniform motion?
If an object moving along the straight line covers equal distances in equal intervals of
time, then it is said to have uniform motion.
8. What is the position - time graph?
A graph of position (along y - axis) against time (along x - axis) is known as position time
graph.
9. Define average velocity.
Average velocity is defined as the displacement (∆x) divided by time interval (∆t).
t
x
t t
x x
v
2 1
2 1
∆
∆
=
−
−
=
−
10. Define average speed.
Average speed is defined as the total path length traveled divided by the total time
taken. Average speed =
total time int erval
path length
11. Define instantaneous velocity of a body in terms of its average velocity.
The instantaneous velocity is defined as the limit of the average velocity as the time
interval ∆t tends to zero.
dt
dx
t
x
v lim v lim
t 0 t 0
=
∆
∆
= =
∆ → ∆ →
−
12. The average velocity of a body is equal to its i