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A group of six toy soldiers standing in a row against an olive green background.straightA boy on the left side of a seesaw is going down, while a girl on the right side is going up.up and downA ceiling fan with three blades rotating.round and roundTwo children on a swing set.back and forthA butterfly flying towards two flowers.random
Question: Every oscillatory motion is periodic but every periodic motion is not oscillatory. Justify the statement with an example.Answer: Oscillatory motion is a to-and-fro motion about a mean position that repeats itself at regular intervals of time (e.g., a simple pendulum, which is both oscillatory and periodic). However, some periodic motions do not involve a to-and-fro movement about a mean position, such as the rotation of the Earth on its axis or the movement of the hands of a clock. Therefore, while all oscillatory motions are periodic, not all periodic motions are oscillatory.
Motion of a rolling ball is an example of:
a. periodic motion.
b. non-periodic motion.
c. vibratory motion.b. non-periodic motion.Motion of a swing is an example of:
a. curvilinear motion.
b. multiple motion.
c. oscillatory motion.c. oscillatory motion.Motion of a flying kite is an example of:
a. random motion.
b. rectilinear motion.
c. rolling motion.a. random motion.
Question: Is the motion of the hands of a clock uniform or non-uniform? Why?Answer: The motion of the hands of a clock is uniform because they cover equal angular distances in equal intervals of time (for example, the minute hand moves through 360 degrees in exactly 60 minutes, maintaining a constant speed).
A spaceship travels from A to B, as illustrated in Fig. 2.24. Given that both the points lie inside Earth’s gravitational field, what will happen to the force of gravity and its weight as it travels from A to B?Force of gravity: Decreases ☐ / Increases ☑Weight: Decreases ☐ / Increases ☑
(Note: As the spaceship travels from point A in space down to point B closer to the Earth’s surface, the distance to the Earth’s center decreases, which causes both the gravitational force and the spaceship’s weight to increase.)Why do astronauts experience weightlessness in space?
a. The gravitational force exerted by the Earth increases.
b. There is no contact force present.
c. They have specially designed spacesuits.
d. All of these.b. There is no contact force present.
Weight of a body of mass 1 kg =
a. 1 kgf.
b. 10 kgf.
c. 100 kgf.a. 1 kgf.SI unit of distance is
a. cm.
b. m.
c. km.b. m.Uniform speed is also known as
a. same speed.
b. normal speed.
c. constant speed.c. constant speed.As the distance of a body increases from the surface of the Earth, the gravitational force acting on it
a. increases.
b. decreases.
c. does not change.b. decreases.
Question: What is the difference between rotatory motion and circulatory motion?Discussion/Answer: In rotatory motion, an object spins around a fixed axis passing through its body (e.g., a spinning top), whereas in circulatory motion, an object moves as a whole along a circular path around a central external point (e.g., a girl swinging a ball on a string).Question: Why does the weight of an object change when it is moved from the equator to the poles?Discussion/Answer: The weight of an object depends on the gravitational force acting on it. Because the Earth’s gravitational force is maximum at the poles and minimum at the equator, an object’s weight will be highest at the poles and lowest at the equator.
Which of the following objects is not at rest with respect to the Earth?
a. an aeroplane parked at the airport
b. a bird sitting on a tree
c. a book kept on a table
d. a train running on a trackd. a train running on a trackThe speed of very fast moving objects is measured in
a. m/s.
b. cm/h.
c. km/h.
d. km/s.c. km/h.The motion of smoke particles is an example of
a. vibratory motion.
b. random motion.
c. translatory motion.
d. oscillatory motion.b. random motion.The distance travelled by a vehicle is recorded by a/an
a. speedometer.
b. odometer.
c. monometer.
d. motometer.b. odometer.In which of the following types of motion, there is no change in the direction of the moving body?
a. curvilinear motion
b. random motion
c. oscillatory motion
d. rectilinear motiond. rectilinear motionStudy the Venn diagram given below and identify the examples for I and II.
a. I - Drill machine, II - Movement of Earth around the Sun
b. I - A ball rolling on the ground, II - Motion of the Earth on its axis
c. I - Pulley, II - Bob of a simple pendulum
d. I - Suitcase wheels, II - Needle of a sewing machineb. I - A ball rolling on the ground, II - Motion of the Earth on its axis
Motion of a potter’s wheel is an example of … motion.rotatoryTwo types of translatory motion are … and …rectilinear and curvilinearDistance travelled by light in one year is called …light yearOne complete to and fro motion of the pendulum about its mean position is called …one oscillationThe weight of a body … as we go higher.decreases
Weight of a body is a constant quantity.False (F)A mango falling from a tree is an example of curvilinear motion.False (F)The SI unit of speed is m/s.True (T)Since distance is always positive, speed is also always positive.True (T)Mass of a body can be zero.False (F)
motion of the Earth about its axisRotatory motion and periodic motionmotion of a car taking a turn on the roadCurvilinear motionmotion of a bullet fired from a gunTranslatory motion (specifically rectilinear motion)motion of a piston of an engineOscillatory motion (also periodic)motion of a spinning wheelRotatory motion
translatory motionDefinition: The motion of an object in which every point of the object moves through the same distance in the same interval of time.Examples: A car moving along a road, a boy going down a slide.circulatory motionDefinition: The motion of an object about a fixed central point along the circumference of a circle.Examples: Children on a merry-go-round, a girl swinging a ball tied to a string in a circular path.oscillatory motionDefinition: The to-and-fro or back-and-forth motion of an object about its mean position.Examples: The motion of a simple pendulum, the motion of a swing.vibratory motionDefinition: The motion of the parts of a body about its mean position.Examples: Plucking the strings of a guitar, playing a drum.multiple motionDefinition: The motion which is a combination of two or more types of motion.Examples: A bicycle (rotatory motion of wheels and translatory motion of the bicycle itself), a drill machine.random motionDefinition: The motion in which an object changes its direction frequently.Examples: A flying mosquito, smoke particles.
When is an object said to be at rest? Give two examples.Answer: An object is said to be at rest if it does not change its position with time in relation to its surroundings.Examples: A chair kept on the floor, a tree rooted to the ground.When is an object said to be in motion? Give two examples.Answer: An object is said to be in motion if it changes its position with time with respect to its surroundings.Examples: A flying bird, a moving car.What is a simple pendulum? Define its oscillation and time period.Answer:Simple pendulum: An arrangement that consists of a small heavy mass (bob) suspended by a weightless, inextensible, and perfectly flexible string from a rigid support.Oscillation: One complete to-and-fro motion of the pendulum about its mean position (e.g., from mean position O to extreme position A, then to extreme position B on the other side, and back to O).Time period: The time taken by the pendulum to complete one oscillation.Why does the mass of a body remain same everywhere?Answer: Mass is the quantity of matter contained in a body. Since the amount of matter in a body is constant and does not depend on gravitational attraction or location, the mass remains the same everywhere.
rectilinear and curvilinear motionRectilinear motion is the motion of an object along a straight line (e.g., an athlete running on a straight racing track), whereas curvilinear motion is the motion of an object along a curved line (e.g., a car taking a turn on a road).periodic and non-periodic motionPeriodic motion is motion that repeats itself at fixed intervals of time (e.g., the revolution of the Earth around the sun), whereas non-periodic motion does not repeat itself at fixed intervals of time (e.g., a ball rolling on the ground and gradually stopping).rest and motionRest is the state of an object when it does not change its position relative to its surroundings with time, whereas motion is the state when an object continuously changes its position relative to its surroundings with time.mass and weightMass is the quantity of matter in a body, is constant everywhere, measured in kilograms (kg) using a beam balance, and can never be zero. Weight is the gravitational force with which the Earth attracts a body, varies from place to place, is measured in newtons (N) using a spring balance, and can be zero where no force of gravity is acting.uniform and non-uniform motionUniform motion occurs when an object covers equal distances in equal intervals of time, whereas non-uniform motion occurs when an object covers unequal distances in equal intervals of time.
Describe an activity to determine the time period of a simple pendulum.Aim: To determine the time period of a simple pendulum.Materials Required: A cork, a metallic bob, silk thread, a stand, a clamp, and a stopwatch.Procedure:Tie the silk thread to the metallic bob at one end and to the cork held by the clamp on the stand at the other end.Displace the bob slightly from its mean position (rest position) and release it so it begins to oscillate freely. Ensure it does not hit any obstacles.Start the stopwatch as the bob passes the mean position and count the number of oscillations.Stop the stopwatch when the bob completes exactly 20 oscillations.Record the time taken (
seconds).Calculate the time period (
) using the formula: 
seconds.Repeat this process multiple times to observe that the time period remains constant at a given place for a fixed length.How are circulatory motion and vibratory motion related to periodic motion? Explain.Explanation:Circulatory motion involves an object moving along a circular path about a fixed central point. When this occurs at a constant speed (such as the hands of a watch or the Earth’s orbit around the sun), the object completes each full loop in equal, predictable intervals of time. Hence, constant-speed circulatory motion is periodic.Vibratory motion is the motion of parts of a body about their mean position. This back-and-forth oscillation of atoms or parts of the body happens in regular, fixed intervals of time (e.g., a plucked string of a guitar, vibrating vocal chords). Since these vibrations repeat periodically, vibratory motion is also a form of periodic motion.
Mayank travels in a straight road from home to school. He takes 10 min to reach point X and further 5 min to reach his school. On his way back, he takes 5 min to reach point X and then 10 minutes to reach home. Which type of motion is shown by Mayank?
a. rectilinear and circulatory motion
b. periodic and rectilinear motion
c. oscillatory and periodic motion
d. rectilinear and non-periodic motiond. rectilinear and non-periodic motionMass of a person is the same on earth and moon, whereas the weight of a person is different. Justify.Justification: Mass is a measure of the amount of matter in a body, which remains constant regardless of location. Weight, however, is the gravitational force acting on a body (
). Because the Earth’s mass is much greater than the Moon’s, its gravitational pull is much stronger (about 6 times stronger). Therefore, a person’s weight on the Earth is significantly greater than on the Moon, even though their mass is identical in both places.
A train travels a distance of 1440 km in 12 hours. Calculate the speed of the train.Given: Distance (
) = 1440 km, Time () = 12 hours
Answer: 120 km/hFind the distance covered by a car travelling at a constant speed of 60 m/s in 10 s.Given: Speed (
) = 60 m/s, Time () = 10 s
Answer: 600 mA bus starting from Bengaluru covers a distance of 300 km in 6 hours on Friday evening, and returns to Bengaluru in 4 hours early next morning. Find its average speed.Given:Distance on Friday (
) = 300 km, Time taken (
) = 6 hDistance on return journey (
) = 300 km, Time taken (
) = 4 hTotal Distance = 
Total Time = 
Answer: 60 km/hTwo cars A and B start moving at the same time. The distances covered by them in a given interval of time are given in the table below. Identify which car has uniform motion and why.Answer: Car A has uniform motion.Reason: The time intervals are all equal (30 minutes each).Car A covers exactly 15 km in every 30-minute interval (
km, 
km, 
km, 
km, 
km). Since it covers equal distances in equal intervals of time, its motion is uniform.Car B covers unequal distances in equal intervals of time (
km, 
km, 
km, 
km, 
km). Its motion is therefore non-uniform.Riya has to complete her journey of 480 km. She travels the first 60 km of her journey at a speed of 30 km/h. What should be the speed for the next 420 km so that the average speed is 70 km/h?Given:Total Distance = 480 km
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Answers to textbook exercises
Prepared by: learnloophq@gmail.com
Chapter: 02. Motion
CHAPTER EXERCISE ANSWERS: MOTION
CONNECT (Page 21)
Select the type of movement exhibited in each of the following pictures from the choices given: (straight, back and forth, round and round, up and down, random)
REASON CORNER (Page 28)
CHECK YOUR PROGRESS (Page 31)
Choose the correct option:
REASON CORNER (Page 34)
PREPPING FOR PISA (Page 37)
CHECK YOUR PROGRESS (Page 37)
Choose the correct option:
MY QUESTION TIME (Page 37)
Frame a question on each of the following topics and discuss their answers:
a. types of motion
b. weight
EVALUATION (Page 39-41)
A. Choose the correct option.
B. Fill in the blanks.
C. Write true (T) or false (F) against the following statements.
D. Name the type or types of motion in the following:
E. Define the following and give two examples of each.
F. Short-answer-type questions.
G. Differentiate between:
H. Long-answer-type questions.
Higher Order Thinking Skills (HOTS)
Numericals
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