SUMMARY: This chapter introduces the concept of force and elaborates on Newton's three laws of motion, explaining their applications and implications in everyday life. KEY TOPICS: force, Newton's first law of motion, inertia, Newton's second law of motion, momentum, Newton's third law of motion, action and reaction forces, balanced and unbalanced forces, conservation of momentum, applications of Newton's laws
What is the definition of force according to Newton's laws?
AA push or pull on an object
BThe mass of an object
CThe speed of an object
DThe distance covered by an object
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Correct answer: Option 1 — A push or pull on an object
Q21 Mark
Which of the following best describes inertia?
AThe tendency of an object to resist changes in its state of motion
BThe force acting on an object
CThe acceleration of an object due to gravity
DThe energy stored in an object
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Correct answer: Option 1 — The tendency of an object to resist changes in its state of motion
Q31 Mark
According to Newton's second law of motion, what is the relationship between force, mass, and acceleration?
AForce is equal to mass times acceleration (F=ma)
BForce is equal to mass divided by acceleration (F=m/a)
CForce is equal to acceleration divided by mass (F=a/m)
DForce is independent of mass and acceleration
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Correct answer: Option 1 — Force is equal to mass times acceleration (F=ma)
Q41 Mark
If an object has a mass of 10 kg and is accelerating at 2 m/s², what is the net force acting on it?
A5 N
B10 N
C20 N
D30 N
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Correct answer: Option 3 — 20 N
Q51 Mark
What does Newton's third law of motion state?
AFor every action, there is an equal and opposite reaction
BAn object in motion stays in motion unless acted upon by a force
CThe acceleration of an object is directly proportional to the net force acting on it
DThe momentum of an object is constant unless acted upon by an external force
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Correct answer: Option 1 — For every action, there is an equal and opposite reaction
Q61 Mark
Which of the following is an example of balanced forces?
AA book resting on a table
BA car accelerating on a highway
CA person pushing a wall
DA ball rolling down a hill
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Correct answer: Option 1 — A book resting on a table
Q71 Mark
What is the unit of momentum?
ANewton
BKilogram meter per second (kg m/s)
CJoule
DKilogram
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Correct answer: Option 2 — Kilogram meter per second (kg m/s)
Q81 Mark
Which of the following scenarios illustrates unbalanced forces?
AA parked car
BA child swinging on a swing
CA satellite orbiting Earth
DA person lifting a heavy box
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Correct answer: Option 4 — A person lifting a heavy box
Q91 Mark
In a closed system, what happens to the total momentum before and after a collision?
AIt increases
BIt decreases
CIt remains constant
DIt becomes zero
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Correct answer: Option 3 — It remains constant
Q101 Mark
If a 5 kg object is moving at a velocity of 3 m/s, what is its momentum?
A15 kg m/s
B8 kg m/s
C3 kg m/s
D5 kg m/s
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Correct answer: Option 1 — 15 kg m/s
Q111 Mark
Which of the following is NOT an application of Newton's laws of motion?
ARocket propulsion
BCar brakes
CElectric current
DSports activities
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Correct answer: Option 3 — Electric current
Q121 Mark
What is the effect of a net force of zero on an object?
AIt will accelerate
BIt will remain at rest or move at constant velocity
CIt will gain momentum
DIt will change direction
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Correct answer: Option 2 — It will remain at rest or move at constant velocity
Q131 Mark
Which law explains why passengers lurch forward in a car when it suddenly stops?
ANewton's first law of motion
BNewton's second law of motion
CNewton's third law of motion
DLaw of conservation of momentum
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Correct answer: Option 1 — Newton's first law of motion
Q141 Mark
When a swimmer pushes the water backwards, what happens according to Newton's third law?
AThe swimmer moves forward
BThe water moves backward
CThe swimmer sinks
DThe water remains still
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Correct answer: Option 1 — The swimmer moves forward
Q151 Mark
What is the primary reason a heavy object requires more force to accelerate than a lighter object?
AIt has more inertia
BIt has less mass
CIt has more momentum
DIt is harder to push
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Correct answer: Option 1 — It has more inertia
Short Answer Questions10 questions
Q163 Marks
What is force and how is it defined in physics?
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Force is defined as an interaction that causes an object to change its velocity, which can include starting, stopping, or changing direction. It is a vector quantity, meaning it has both magnitude and direction.
Q173 Marks
State Newton's first law of motion and explain its significance.
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Newton's first law of motion states that an object at rest will remain at rest, and an object in motion will continue in motion with the same speed and in the same direction unless acted upon by an unbalanced force. This law highlights the concept of inertia and the need for a force to change the state of motion.
Q183 Marks
What is inertia and how does it relate to Newton's first law?
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Inertia is the tendency of an object to resist changes in its state of motion. According to Newton's first law, an object will maintain its state of rest or uniform motion unless acted upon by an external force, illustrating the concept of inertia.
Q193 Marks
Explain Newton's second law of motion and its formula.
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Newton's second law of motion states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. The formula is F = ma, where F is the net force, m is the mass, and a is the acceleration.
Q203 Marks
What is momentum and how is it calculated?
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Momentum is the product of an object's mass and its velocity, representing the quantity of motion an object has. It is calculated using the formula p = mv, where p is momentum, m is mass, and v is velocity.
Q213 Marks
Describe Newton's third law of motion with an example.
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Newton's third law of motion states that for every action, there is an equal and opposite reaction. For example, when a person jumps off a small boat, the action of pushing down on the boat causes the boat to push back up and move in the opposite direction.
Q223 Marks
What are balanced and unbalanced forces? Provide examples.
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Balanced forces are equal in magnitude and opposite in direction, resulting in no change in motion, such as two people pushing a car in opposite directions with equal force. Unbalanced forces result in a change in motion, like when a person pushes a stationary car, causing it to move.
Q233 Marks
How does the conservation of momentum apply in a collision?
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The conservation of momentum states that in a closed system, the total momentum before a collision is equal to the total momentum after the collision. This principle helps analyze the outcomes of collisions, such as in billiard balls or car crashes.
Q243 Marks
Explain how Newton's laws of motion apply to everyday activities like walking.
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When walking, Newton's third law is evident as the foot pushes backward against the ground (action), and the ground pushes the foot forward (reaction), allowing movement. Additionally, the second law applies as the force exerted by the legs causes acceleration, enabling walking.
Q253 Marks
What is the relationship between mass, force, and acceleration as per Newton's second law?
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According to Newton's second law, the relationship is defined by the equation F = ma, indicating that the force acting on an object is equal to the mass of the object multiplied by its acceleration. This means that for a given force, an increase in mass results in a decrease in acceleration.
Long Answer Questions6 questions
Q266 Marks
Explain Newton's first law of motion and provide an example from everyday life that illustrates this law.
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Newton's first law of motion states that an object at rest will remain at rest, and an object in motion will continue to move at a constant velocity unless acted upon by a net external force. This principle is often referred to as the law of inertia. For example, when a car suddenly stops, passengers inside the car lurch forward because their bodies tend to continue moving in the direction the car was traveling until an external force (the seatbelt or the dashboard) acts on them to stop their motion.
Q276 Marks
Describe the concept of inertia and how it relates to mass. Provide examples to support your explanation.
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Inertia is the property of an object to resist changes in its state of motion. The greater the mass of an object, the greater its inertia. This means that heavier objects require more force to change their motion compared to lighter objects. For instance, it is much easier to push a small toy car than it is to push a full-sized car. The toy car has less mass and therefore less inertia, while the full-sized car has more mass and greater inertia, making it harder to accelerate or stop.
Q286 Marks
State Newton's second law of motion and derive the relationship between force, mass, and acceleration. Provide an example to illustrate this relationship.
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Newton's second law of motion states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. This relationship can be expressed with the formula F = ma, where F is the net force, m is the mass, and a is the acceleration. For example, if a 10 kg object is pushed with a force of 20 N, the acceleration can be calculated as a = F/m = 20 N / 10 kg = 2 m/s². This shows how the force applied affects the acceleration of the object.
Q296 Marks
What is momentum, and how is it calculated? Discuss the principle of conservation of momentum with an example.
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Momentum is defined as the product of an object's mass and its velocity, represented by the formula p = mv, where p is momentum, m is mass, and v is velocity. The principle of conservation of momentum states that in a closed system, the total momentum before an event (like a collision) is equal to the total momentum after the event. For example, if two ice skaters push off each other, the momentum they have before they push off is equal to the momentum they have after they separate, demonstrating that momentum is conserved in the absence of external forces.
Q306 Marks
Explain Newton's third law of motion and provide an example that demonstrates action and reaction forces.
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Newton's third law of motion states that for every action, there is an equal and opposite reaction. This means that forces always occur in pairs; when one object exerts a force on a second object, the second object exerts a force of equal magnitude and opposite direction on the first object. An example of this is when a swimmer pushes the water backwards with their hands; the reaction force pushes the swimmer forward, allowing them to move through the water.
Q316 Marks
Differentiate between balanced and unbalanced forces. Provide real-life examples of each.
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Balanced forces are forces that are equal in size and opposite in direction, resulting in no change in motion. For example, when a book rests on a table, the gravitational force pulling it down is balanced by the normal force exerted by the table pushing it up. Unbalanced forces, on the other hand, result in a change in motion. For instance, when a person pushes a stationary car, the force applied is greater than the opposing forces (like friction), causing the car to move. This distinction is crucial in understanding how forces affect motion.
Assertion–Reason Questions8 questions
Q321 Mark
Assertion (A): An object at rest will remain at rest unless acted upon by an external force.
Reason (R): This statement is a direct application of Newton's first law of motion.
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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): Inertia is the tendency of an object to resist changes in its state of motion.
Reason (R): Inertia is directly related to the mass 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.
Q341 Mark
Assertion (A): The acceleration of an object is directly proportional to the net force acting on it.
Reason (R): This is described by Newton's second law of motion, which states F=ma.
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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): Momentum is conserved in a closed system.
Reason (R): This principle is a consequence of Newton's third law of motion.
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Correct answer: Option 2 —
Both A and R are true, but R is not the correct explanation of A.
Q361 Mark
Assertion (A): For every action, there is an equal and opposite reaction.
Reason (R): This statement describes Newton's first law of motion.
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Correct answer: Option 3 —
A is true, but R is false.
Q371 Mark
Assertion (A): Balanced forces acting on an object will cause it to accelerate.
Reason (R): Balanced forces result in a net force of zero, thus no acceleration occurs.
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Correct answer: Option 4 —
A is false, but R is true.
Q381 Mark
Assertion (A): An object in motion will continue to move at a constant velocity unless acted upon by an unbalanced force.
Reason (R): This is a restatement of Newton's first law of 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): The greater the mass of an object, the greater the force required to achieve the same acceleration.
Reason (R): This is explained by Newton's second law of motion.
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Correct answer: Option 1 —
Both A and R are true, and R is the correct explanation of A.
Statement-Based Questions8 questions
Q401 Mark
Statement 1: A force is a push or pull acting on an object.
Statement 2: Inertia is the tendency of an object to remain at rest or in uniform motion unless acted upon by a net external force.
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Correct answer: Option 1 —
Both statements are true.
Q411 Mark
Statement 1: Newton's first law states that an object will accelerate if a net force acts on it.
Statement 2: An object at rest will remain at rest unless acted upon by a net external force.
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Correct answer: Option 2 —
Only Statement 1 is true.
Q421 Mark
Statement 1: Momentum is defined as the product of mass and velocity.
Statement 2: According to Newton's second law, force is equal to mass times acceleration.
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Correct answer: Option 1 —
Both statements are true.
Q431 Mark
Statement 1: Balanced forces acting on an object will cause it to accelerate.
Statement 2: Unbalanced forces can change the state of motion of an object.
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Correct answer: Option 3 —
Only Statement 2 is true.
Q441 Mark
Statement 1: Newton's third law states that for every action, there is an equal and opposite reaction.
Statement 2: The conservation of momentum applies only in elastic collisions.
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Correct answer: Option 2 —
Only Statement 1 is true.
Q451 Mark
Statement 1: Inertia is directly proportional to the mass of an object.
Statement 2: A heavier object has more inertia than a lighter object.
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Correct answer: Option 1 —
Both statements are true.
Q461 Mark
Statement 1: An object in motion will continue in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
Statement 2: Friction is an example of an unbalanced force.
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Correct answer: Option 1 —
Both statements are true.
Q471 Mark
Statement 1: The formula for calculating momentum is p = mv, where p is momentum, m is mass, and v is velocity.
Statement 2: Momentum is conserved in all types of collisions.
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Correct answer: Option 2 —
Only Statement 1 is true.
