Chapter 9 - Motion and Types of Motion
1. Identify the types of motion.
(a) Movement of the earth around the sun : ………. .
Ans: Circular motion, periodic motion.
(b) Movement of a ceiling fan : ……….
Ans: Oscillatory motion, circular motion.
(c) A meteor falling from the sky : ………. .
Ans: Linear motion.
(d) A rocket launched from the ground : ……….
Ans: Linear motion.
(e) A fish swimming in water : ……….
Ans: Random motion.
(f) The plucked string of a sitar : …….
Ans: Oscillatory motion.
2. Fill in the blanks.
(a) If a ball is released from the terrace of a building, it comes down in ……….. motion. On the other hand, it reaches the ground in ……….. motion if it is thrown with force away from the terrace in a direction parallel to the terrace.
Ans: uniform linear, random
(b) The motion of an aeroplane on the runway before take-off is………. .
Ans: linear.
(c) The kite looking for its prey flies with ………. motion in the sky.
Ans: circular
(d) Children sitting in a rotating giant wheel have ……….. motion, while those sitting in a merry-go-round have a ……….. motion.
Ans: uniform circular, non-uniform circular
(Linear, non-linear, circular, uniform linear, non-uniform linear, uniform circular, non-uniform circular, random)
3. How are we different?
(a) Oscillatory motion and linear motion.
Ans:
| Oscillatory motion | Linear motion |
|---|---|
(i) The motion of a body that is oscillating, i.e., swinging back and forth, is called oscillatory motion. | (i) The motion of an object in a straight line or in the same direction is called linear motion. |
(ii) The object showing oscillatory motion comes back to its original place again and again. | (ii) The object showing linear motion is displaced from its original place. |
(iii) For example, the pendulum of a clock, the needle of a sewing machine, etc. | (iii) For example, the pendulum of a clock, the needle of a sewing machine, etc. |
(b) Linear motion and random motion.
Ans:
| Linear motion | Random motion |
|---|---|
(i) The motion of an object in a straight line or in the same direction is called linear motion. | (i) The motion that changes its direction and speed continuously is called random motion. |
(ii) The object showing linear motion is displaced from its original place. | (ii) Objects displaying random motion never travel in a straight line. |
(iii) For example, the pendulum of a clock, the needle of a sewing machine, etc. | (iii) For example, flying birds, swimming fish, etc. |
(c) Random motion and oscillatory motion.
Ans:
| Random motion | Oscillatory motion |
|---|---|
(i) The motion that changes its direction and speed continuously is called random motion. | (i) The motion of a body that is oscillating, i.e., swinging back and forth, is called oscillatory motion. |
(ii) Objects displaying random motion never travel in a straight line. | (ii) The object showing oscillatory motion comes back to its original place again and again. |
(iii) For example, flying birds, swimming fish, etc. | (iii) For example, the pendulum of a clock, the needle of a sewing machine, etc. |
4. Explain in your own words, giving one example each.
(a) Linear motion
Ans: The motion of an object in a straight line or in the same direction is called linear motion.
Example: The motion of a moving car on a straight road.
(b) Oscillatory motion
Ans: The motion of a body that is oscillating, i.e., swinging back and forth, is called oscillatory motion.
Example: The movement of the pendulum of a clock is an example of oscillatory motion.
(c) Circular motion
Ans: The motion of an object along a circular path is called circular motion.
Example: The hands of a clock move in a circular manner.
(d) Random motion
Ans: The motion that continuously changes its direction and speed is called random motion.
Example: A butterfly that constantly flits from one flower to another is in random motion.
(e) Periodic motion
Ans: The motion of an object that passes through a certain point again and again after a fixed period is called periodic motion.
Example: The minute hand of a clock completes one round in exactly 60 minutes every time, showing periodic motion.
5. Answer the following questions in your own words.
(a) Which types of motion are seen in birds flying in the sky?
Ans: There are different types of motions that can be seen in birds flying in the sky. They are:
(i) Random motion: It occurs when birds fly irregularly with continuous changes in the direction of motion and speed. Example: Crow.
(ii) Oscillatory motion: It occurs when birds flap their wings.
(iii) Linear motion: It occurs when birds fly in a straight line.
(b) Write in detail about your experience of various types of motion while riding a bicycle on a road.
Ans: There are various types of motions experienced while riding a bicycle on the road. They are:
(i) Uniform or non-uniform linear motion occurs when a bicycle moves in a straight line.
(ii) The motion of the legs of a person riding a bicycle is in a uniform or non-uniform circular motion.
(iii) The wheels of the bicycle are in uniform or non-uniform circular motion.
6. Complete the puzzle using words for types of motion :
(1) a spring is stretched and one end is released
(2) a minute hand
(3) a seesaw
(4-5) children in a march past
(6) a stone rolling down a hillside.
Solution:
(1) A spring is stretched, and one end is released.
Ans: The motion of a body that is oscillating, i.e., swinging back and forth, is called oscillatory motion.
(2) A minute hand:
Ans: The minute hand of a clock has a circular motion. In circular motion, an object moves such that its distance from a fixed point remains the same.
(3) a see-saw:
Ans: The motion of an object that passes through a certain point again and again after a fixed period is called periodic motion.
(4-5) children in a march past:
Ans: Uniform linear motion occurs when an object’s distance traversed along a straight line in unit time is consistently the same.
(6) a stone rolling down a hillside:
Ans: The motion that changes its direction and speed continuously is called random motion.
