SUMMARY: The chapter "Motion" in Class 9 Science introduces the concept of motion and explores the various types of motion and the laws governing them. KEY TOPICS: distance and displacement, speed and velocity, uniform and non-uniform motion, acceleration, equations of motion, graphical representation of motion, uniform circular motion
What is the difference between distance and displacement?
ADistance is a scalar quantity, while displacement is a vector quantity.
BDistance is a vector quantity, while displacement is a scalar quantity.
CBoth distance and displacement are scalar quantities.
DBoth distance and displacement are vector quantities.
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Correct answer: Option 1 — Distance is a scalar quantity, while displacement is a vector quantity.
Q21 Mark
Which of the following represents uniform motion?
AA car moving at a constant speed in a straight line.
BA bicycle accelerating from rest.
CA train coming to a stop.
DA person walking in a circular path.
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Correct answer: Option 1 — A car moving at a constant speed in a straight line.
Q31 Mark
If a car travels 100 meters in 5 seconds, what is its speed?
A20 m/s
B25 m/s
C15 m/s
D30 m/s
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Correct answer: Option 2 — 25 m/s
Q41 Mark
Which of the following is an example of non-uniform motion?
AA ball rolling down a hill.
BA train moving at a constant speed on a straight track.
CA car cruising on a highway.
DA person walking at a steady pace.
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Correct answer: Option 1 — A ball rolling down a hill.
Q51 Mark
What is the acceleration of an object that changes its velocity from 20 m/s to 50 m/s in 10 seconds?
A3 m/s²
B5 m/s²
C2 m/s²
D4 m/s²
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Correct answer: Option 2 — 5 m/s²
Q61 Mark
Which of the following equations of motion relates final velocity, initial velocity, acceleration, and time?
Av = u + at
Bs = ut + 1/2 at²
Cv² = u² + 2as
Ds = vt
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Correct answer: Option 1 — v = u + at
Q71 Mark
In a velocity-time graph, what does the slope represent?
ADistance
BSpeed
CAcceleration
DDisplacement
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Correct answer: Option 3 — Acceleration
Q81 Mark
What is the displacement of an object that moves 5 meters east and then 5 meters west?
A10 meters east
B0 meters
C5 meters west
D5 meters east
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Correct answer: Option 2 — 0 meters
Q91 Mark
Which of the following describes uniform circular motion?
AAn object moving in a straight line at constant speed.
BAn object moving in a circular path at constant speed.
CAn object accelerating in a straight line.
DAn object moving back and forth in a line.
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Correct answer: Option 2 — An object moving in a circular path at constant speed.
Q101 Mark
If an object is moving with a constant speed of 10 m/s, how far will it travel in 15 seconds?
A150 meters
B100 meters
C200 meters
D50 meters
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Correct answer: Option 1 — 150 meters
Q111 Mark
An object is said to be in motion if it changes its position with respect to:
ATime
BA reference point
CSpeed
DAcceleration
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Correct answer: Option 2 — A reference point
Q121 Mark
What is the term for the rate of change of velocity?
ASpeed
BAcceleration
CDisplacement
DDistance
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Correct answer: Option 2 — Acceleration
Q131 Mark
Which of the following equations can be used to calculate the distance traveled under uniform acceleration?
As = ut + 1/2 at²
Bv = u + at
Cv² = u² + 2as
Ds = vt
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Correct answer: Option 1 — s = ut + 1/2 at²
Q141 Mark
In a distance-time graph, a flat line indicates that the object is:
AAccelerating
BAt rest
CMoving at constant speed
DMoving with increasing speed
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Correct answer: Option 2 — At rest
Q151 Mark
What is the final velocity of an object that starts from rest and accelerates at 4 m/s² for 5 seconds?
A10 m/s
B20 m/s
C15 m/s
D25 m/s
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Correct answer: Option 1 — 10 m/s
Short Answer Questions10 questions
Q163 Marks
Define distance and displacement. How do they differ from each other?
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Distance is the total path length covered by an object in motion, regardless of direction. Displacement, on the other hand, is the shortest straight-line distance from the initial to the final position of the object, along with the direction. Thus, distance is a scalar quantity, while displacement is a vector quantity.
Q173 Marks
What is speed? How is it different from velocity?
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Speed is the rate at which an object covers distance, calculated as distance divided by time. Velocity, however, is the rate of change of displacement and includes direction, making it a vector quantity. Therefore, while speed is a scalar, velocity is a vector.
Q183 Marks
Explain uniform motion with an example.
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Uniform motion occurs when an object covers equal distances in equal intervals of time, regardless of the duration of the time intervals. For example, a car moving at a constant speed of 60 km/h on a straight road is in uniform motion.
Q193 Marks
What is non-uniform motion? Provide an example.
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Non-uniform motion occurs when an object covers unequal distances in equal intervals of time. An example is a car that accelerates from a stoplight, covering different distances in each second as it speeds up.
Q203 Marks
Define acceleration. How can it be positive or negative?
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Acceleration is the rate of change of velocity of an object with respect to time. It can be positive when an object speeds up, and negative (also known as deceleration) when an object slows down, indicating a decrease in velocity.
Q213 Marks
What are the three equations of motion? Briefly describe each.
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The three equations of motion are: 1) v = u + at, which relates final velocity (v) to initial velocity (u), acceleration (a), and time (t); 2) s = ut + 1/2 at², which calculates displacement (s) based on initial velocity, time, and acceleration; 3) v² = u² + 2as, which connects the final velocity, initial velocity, acceleration, and displacement without involving time.
Q223 Marks
How can graphical representation be used to analyze motion?
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Graphical representation, such as distance-time and velocity-time graphs, helps visualize the motion of an object. The slope of a distance-time graph indicates speed, while the slope of a velocity-time graph indicates acceleration. Areas under the velocity-time graph can also represent displacement.
Q233 Marks
What is uniform circular motion? Give an example.
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Uniform circular motion refers to the motion of an object traveling in a circular path at a constant speed. An example is a satellite orbiting the Earth, where it maintains a constant speed while continuously changing direction.
Q243 Marks
Explain the difference between average speed and instantaneous speed.
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Average speed is calculated by dividing the total distance traveled by the total time taken, giving an overall rate of motion. Instantaneous speed, however, is the speed of an object at a specific moment in time, often measured using a speedometer in a vehicle.
Q253 Marks
What is the significance of the slope in a distance-time graph?
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The slope of a distance-time graph indicates the speed of the object. A steeper slope represents a higher speed, while a horizontal line indicates that the object is at rest, as there is no change in distance over time.
Long Answer Questions6 questions
Q266 Marks
Define distance and displacement. How are they different from each other? Provide examples to illustrate your answer.
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Distance is a scalar quantity that represents the total path length covered by an object in motion, regardless of direction. Displacement, on the other hand, is a vector quantity that represents the shortest straight line distance from the initial to the final position of the object, along with the direction. For example, if a person walks 3 km east and then 4 km west, the distance covered is 7 km, but the displacement is 1 km west.
Q276 Marks
What is speed and how does it differ from velocity? Explain with examples.
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Speed is a scalar quantity that measures how fast an object is moving, defined as the distance traveled per unit of time. Velocity, however, is a vector quantity that includes both the speed of the object and the direction of its motion. For instance, if a car travels 60 km in 1 hour, its speed is 60 km/h. If it travels 60 km east in the same time, its velocity is 60 km/h east.
Q286 Marks
Explain uniform and non-uniform motion with examples. How can we identify each type of motion in real life?
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Uniform motion occurs when an object covers equal distances in equal intervals of time, such as a train moving at a constant speed of 80 km/h. Non-uniform motion, on the other hand, occurs when an object covers unequal distances in equal intervals of time, like a car accelerating from a stoplight. We can identify uniform motion by observing a constant speed on a speedometer, while non-uniform motion can be identified by varying speeds or changes in direction.
Q296 Marks
What is acceleration? How is it calculated? Provide an example of a situation involving acceleration.
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Acceleration is the rate of change of velocity of an object with respect to time. It can be calculated using the formula: acceleration = (final velocity - initial velocity) / time taken. For example, if a car increases its speed from 20 m/s to 50 m/s in 5 seconds, the acceleration would be (50 m/s - 20 m/s) / 5 s = 6 m/s².
Q306 Marks
State and explain the three equations of motion. How are they useful in solving problems related to motion?
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The three equations of motion are: 1) v = u + at, where v is final velocity, u is initial velocity, a is acceleration, and t is time; 2) s = ut + (1/2)at², where s is displacement; and 3) v² = u² + 2as. These equations are useful for calculating unknown variables in problems involving linear motion, allowing us to relate distance, speed, acceleration, and time effectively.
Q316 Marks
Describe how to graphically represent motion. What information can be derived from a distance-time graph?
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Motion can be graphically represented using distance-time graphs, where the x-axis represents time and the y-axis represents distance. The slope of the graph indicates the speed of the object; a steeper slope represents higher speed. If the graph is a straight line, the motion is uniform, while a curved line indicates non-uniform motion. The area under the graph can also provide insights into the total distance traveled over time.
Assertion–Reason Questions8 questions
Q321 Mark
Assertion (A): Distance is a scalar quantity that refers to how much ground an object has covered during its motion.
Reason (R): Displacement is a vector quantity that refers to the change in position of an object.
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Correct answer: Option 1 —
Both A and R are true, and R is the correct explanation of A.
Q331 Mark
Assertion (A): Speed is defined as the distance traveled per unit time.
Reason (R): Velocity is defined as the displacement per unit time.
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Correct answer: Option 1 —
Both A and R are true, and R is the correct explanation of A.
Q341 Mark
Assertion (A): Uniform motion occurs when an object covers equal distances in equal intervals of time.
Reason (R): Non-uniform motion occurs when an object covers unequal distances in equal intervals of time.
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Correct answer: Option 1 —
Both A and R are true, and R is the correct explanation of A.
Q351 Mark
Assertion (A): Acceleration is the rate of change of velocity.
Reason (R): A body in uniform motion has a constant speed and direction, hence it has zero acceleration.
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Correct answer: Option 1 —
Both A and R are true, and R is the correct explanation of A.
Q361 Mark
Assertion (A): The equation of motion v = u + at can be used to find the final velocity of an object.
Reason (R): This equation is applicable only when the acceleration is constant.
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Correct answer: Option 1 —
Both A and R are true, and R is the correct explanation of A.
Q371 Mark
Assertion (A): Graphical representation of motion can help visualize the distance-time relationship.
Reason (R): A straight line on a distance-time graph indicates uniform motion.
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Correct answer: Option 1 —
Both A and R are true, and R is the correct explanation of A.
Q381 Mark
Assertion (A): In uniform circular motion, the speed of the object remains constant.
Reason (R): The direction of the object's velocity changes continuously in uniform circular motion.
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Correct answer: Option 1 —
Both A and R are true, and R is the correct explanation of A.
Q391 Mark
Assertion (A): Displacement can never be greater than distance.
Reason (R): Displacement is the shortest path between the initial and final position of an object.
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Correct answer: Option 2 —
Both A and R are true, but R is not the correct explanation of A.
Statement-Based Questions8 questions
Q401 Mark
Statement 1: Distance is a scalar quantity while displacement is a vector quantity.
Statement 2: Speed is a vector quantity while velocity is a scalar quantity.
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Correct answer: Option 2 —
Only Statement 1 is true.
Q411 Mark
Statement 1: An object moving in a circular path at a constant speed is said to be in uniform circular motion.
Statement 2: In uniform circular motion, the velocity of the object remains constant.
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Correct answer: Option 3 —
Only Statement 2 is true.
Q421 Mark
Statement 1: Acceleration can be positive, negative, or zero.
Statement 2: An object moving with uniform motion has zero acceleration.
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Correct answer: Option 1 —
Both statements are true.
Q431 Mark
Statement 1: The formula for calculating speed is distance divided by time.
Statement 2: Velocity is calculated by dividing displacement by time.
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Correct answer: Option 1 —
Both statements are true.
Q441 Mark
Statement 1: In non-uniform motion, the speed of the object remains constant.
Statement 2: In non-uniform motion, the speed of the object changes with time.
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Correct answer: Option 3 —
Only Statement 2 is true.
Q451 Mark
Statement 1: The area under a velocity-time graph represents the distance traveled.
Statement 2: The slope of a distance-time graph represents speed.
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Correct answer: Option 1 —
Both statements are true.
Q461 Mark
Statement 1: Displacement can be greater than distance in certain cases.
Statement 2: Distance is always equal to or greater than displacement.
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Correct answer: Option 2 —
Only Statement 1 is true.
Q471 Mark
Statement 1: Acceleration is the rate of change of velocity.
Statement 2: A body can have acceleration even if its speed is constant.
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Correct answer: Option 1 —
Both statements are true.
