Sunil Sureka
8. MOTION
1. Define the followings.
a) Locomotion: The motion which results in change of position from one place to
another is called locomotion. It is seen in case of animals.
b) Rectilinear (or Translatory motion): The motion of an object along a straight line is
called rectilinear or translatory motion.
c) Point object: A point object is one which has no linear direction but posses mass. But
in physics an object is termed as point object, if the distance moved by it is very large
as compared to its dimension.
Example – Earth is treated as point object during revolution around the sun.
d) Rest: An object is said to be at rest, if it does not change its position with respect to
time and its surrounding.
e) Motion: An object is said to be in motion, if it change its position with respect to time
and its surrounding.
f) Distance: Irrespective of the direction in which the body moves, the actual length of
the path travelled by a moving body is known as the distance travelled by a body. It
is a scalar quantity.
g) Displacement: The shortest distance of a moving body from the point of origin
(initial position of the body) to the destination point (final position of the body) is
called displacement. It is vector quantity.
h) Scalar quantity: The physical quantity, which is expressed only by its magnitude, is
called scalar quantity.
Example – distance, speed etc.
i) Vector quantity: The physical quantity, which is expressed completely by both
magnitude and direction, is called vector quantity.
Example – displacement, Velocity etc
2. Rest and motion are relative terms. Explain with an example
Rest and motion are the terms, which are apparently opposite to one another. However,
sometimes it becomes difficult to say whether a body is at rest or in motion.
Example – Two persons A and B sitting on a moving train. The motion of A and B are
same as that of train. Therefore, A is at rest with respect to B. But A and B are in motion
with respect to a person, say ‘C’, standing on the platform. Thus, the two persons A and B
may be in motion with respect to C, but they are at rest with respect to one another. Hence,
rest and motion are relative terms.
3. What are the characteristics of the moving body?
The characteristics of a moving body are as follows –
a) There must be a reference point (Stationary object to describe the position of a given
body)
b) The position of the given body must continuously change with respect to the
reference point.
Page 1 of 23
,Sunil Sureka
4. Give difference between distance and displacement.
Sl. no. DISTANCE DISPLACEMENT
Distance is the actual length of the The shortest distance of a moving body
path travelled by a moving body, from the point of origin to the destination
a.
irrespective of the direction in which point is called displacement.
the body moves.
b. It is a scalar quantity. It is a vector quantity.
c. It cannot be negative or zero. It can be negative, positive or zero.
Distance can be equal to or greater Displacement can be equal to or less than
d.
than displacement. distance.
e. Distance can never decrease with time. Displacement can decrease with time.
5. What do you mean by uniform motion? Give example.
When a body covers equal distance in equal interval of time, then the body is said to be
moving with uniform motion.
Examples:
a) A train running at a speed of 90 Km/hr.
b) Light energy travelling at a speed of 3 x 108 m/s.
6. What do you mean by non-uniform motion? Give example
When a body covers unequal distance in equal interval of time then the body is said to
be moving with a non-uniform motion.
Example –
a) A freely falling stone under the gravity.
b) When brakes are applied on a speeding car.
7. Define speed
The distance travelled by a moving body in unit time is called speed. It is scalar
quantity.
8. Give the mathematical expression of speed.
Distance
Speed = --------------------------
Time
9. Define average speed.
The rate of average distance travelled by a moving body, when the body is moving with
the variable speed is called average speed.
10. Give the mathematical expression for average speed.
Total Distance
Average speed = --------------------------
Total Time
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, Sunil Sureka
11. What are the SI and CGS unit of speed?
Metre (m)
a) S.I unit of speed = ----------------- or (ms-1)
Second (s)
Centimetre (cm)
b) C.G.S unit of speed = ------------------------ or (cms-1)
Second (s)
12. Define velocity
The distance travelled by a moving body in unit time in a particular direction is called
velocity. It is a vector quantity.
13. Give the mathematical expression for velocity.
Displacement (s)
Velocity (v) = --------------------------
Time (t)
s
Or, v = -------
t
14. Give the S.I and CGS unit of velocity
Metre (m)
a) S.I unit of Velocity = ----------------- or (ms-1)
Second (s)
Centimetre (cm)
b) C.G.S unit of Velocity = ------------------------ or (cms-1)
Second (s)
15. Give the mathematical expression of average velocity.
Initial velocity + Final velocity
Average velocity = ---------------------------------------------------
2
u+v
Or, Average velocity =-------------------------
2
(*) The above formula is applicable only if the velocity of an object changes at uniform rate.
16. Define uniform velocity
When a body covers equal distance in equal interval of time, in a particular direction,
then the body is said to have uniform velocity.
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8. MOTION
1. Define the followings.
a) Locomotion: The motion which results in change of position from one place to
another is called locomotion. It is seen in case of animals.
b) Rectilinear (or Translatory motion): The motion of an object along a straight line is
called rectilinear or translatory motion.
c) Point object: A point object is one which has no linear direction but posses mass. But
in physics an object is termed as point object, if the distance moved by it is very large
as compared to its dimension.
Example – Earth is treated as point object during revolution around the sun.
d) Rest: An object is said to be at rest, if it does not change its position with respect to
time and its surrounding.
e) Motion: An object is said to be in motion, if it change its position with respect to time
and its surrounding.
f) Distance: Irrespective of the direction in which the body moves, the actual length of
the path travelled by a moving body is known as the distance travelled by a body. It
is a scalar quantity.
g) Displacement: The shortest distance of a moving body from the point of origin
(initial position of the body) to the destination point (final position of the body) is
called displacement. It is vector quantity.
h) Scalar quantity: The physical quantity, which is expressed only by its magnitude, is
called scalar quantity.
Example – distance, speed etc.
i) Vector quantity: The physical quantity, which is expressed completely by both
magnitude and direction, is called vector quantity.
Example – displacement, Velocity etc
2. Rest and motion are relative terms. Explain with an example
Rest and motion are the terms, which are apparently opposite to one another. However,
sometimes it becomes difficult to say whether a body is at rest or in motion.
Example – Two persons A and B sitting on a moving train. The motion of A and B are
same as that of train. Therefore, A is at rest with respect to B. But A and B are in motion
with respect to a person, say ‘C’, standing on the platform. Thus, the two persons A and B
may be in motion with respect to C, but they are at rest with respect to one another. Hence,
rest and motion are relative terms.
3. What are the characteristics of the moving body?
The characteristics of a moving body are as follows –
a) There must be a reference point (Stationary object to describe the position of a given
body)
b) The position of the given body must continuously change with respect to the
reference point.
Page 1 of 23
,Sunil Sureka
4. Give difference between distance and displacement.
Sl. no. DISTANCE DISPLACEMENT
Distance is the actual length of the The shortest distance of a moving body
path travelled by a moving body, from the point of origin to the destination
a.
irrespective of the direction in which point is called displacement.
the body moves.
b. It is a scalar quantity. It is a vector quantity.
c. It cannot be negative or zero. It can be negative, positive or zero.
Distance can be equal to or greater Displacement can be equal to or less than
d.
than displacement. distance.
e. Distance can never decrease with time. Displacement can decrease with time.
5. What do you mean by uniform motion? Give example.
When a body covers equal distance in equal interval of time, then the body is said to be
moving with uniform motion.
Examples:
a) A train running at a speed of 90 Km/hr.
b) Light energy travelling at a speed of 3 x 108 m/s.
6. What do you mean by non-uniform motion? Give example
When a body covers unequal distance in equal interval of time then the body is said to
be moving with a non-uniform motion.
Example –
a) A freely falling stone under the gravity.
b) When brakes are applied on a speeding car.
7. Define speed
The distance travelled by a moving body in unit time is called speed. It is scalar
quantity.
8. Give the mathematical expression of speed.
Distance
Speed = --------------------------
Time
9. Define average speed.
The rate of average distance travelled by a moving body, when the body is moving with
the variable speed is called average speed.
10. Give the mathematical expression for average speed.
Total Distance
Average speed = --------------------------
Total Time
Page 2 of 23
, Sunil Sureka
11. What are the SI and CGS unit of speed?
Metre (m)
a) S.I unit of speed = ----------------- or (ms-1)
Second (s)
Centimetre (cm)
b) C.G.S unit of speed = ------------------------ or (cms-1)
Second (s)
12. Define velocity
The distance travelled by a moving body in unit time in a particular direction is called
velocity. It is a vector quantity.
13. Give the mathematical expression for velocity.
Displacement (s)
Velocity (v) = --------------------------
Time (t)
s
Or, v = -------
t
14. Give the S.I and CGS unit of velocity
Metre (m)
a) S.I unit of Velocity = ----------------- or (ms-1)
Second (s)
Centimetre (cm)
b) C.G.S unit of Velocity = ------------------------ or (cms-1)
Second (s)
15. Give the mathematical expression of average velocity.
Initial velocity + Final velocity
Average velocity = ---------------------------------------------------
2
u+v
Or, Average velocity =-------------------------
2
(*) The above formula is applicable only if the velocity of an object changes at uniform rate.
16. Define uniform velocity
When a body covers equal distance in equal interval of time, in a particular direction,
then the body is said to have uniform velocity.
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