Q1. What happens to an object when unbalanced forces act on it?
a) It continues moving at the same velocity
b) Its motion remains unchanged
c) It accelerates
d) It vanishes
Answer: c) It accelerates
Explanation: An object accelerates when unbalanced forces act on it. This change can be in the form of a change in speed, direction, or both.
Q2. Which of the following is true according to Newton’s First Law of Motion?
a) An object at rest stays at rest, and an object in motion stays in motion with the same speed and direction unless acted upon by an unbalanced force.
b) The rate of change of momentum of an object is proportional to the applied unbalanced force in the direction of the force.
c) For every action, there is an equal and opposite reaction.
d) Gravity is the only force acting at a distance.
Answer: a) An object at rest stays at rest, and an object in motion stays in motion with the same speed and direction unless acted upon by an unbalanced force.
Explanation: Newton’s First Law of Motion, also known as the Law of Inertia, states that an object will remain at rest or in uniform motion in a straight line unless acted upon by an external force.
Q3. What is inertia?
a) The force required to stop an object
b) The resistance of any physical object to a change in its state of motion or rest
c) The gravitational pull on an object
d) The acceleration due to an applied force
Answer: b) The resistance of any physical object to a change in its state of motion or rest
Explanation: Inertia is the property of matter by which it retains its state of rest or its velocity along a straight line so long as it is not acted upon by an external force.
Q4. According to Newton’s Second Law of Motion, the force on an object is equal to the mass of the object multiplied by its acceleration. This is expressed as F = ma. What does ‘F’ stand for in this equation?
a) Friction
b) Frequency
c) Force
d) Final velocity
Answer: c) Force
Explanation: In the equation F = ma, ‘F’ stands for force, ‘m’ stands for mass, and ‘a’ stands for acceleration. This law quantifies the force on an object and is directly proportional to the acceleration and mass of the object.
Q5. When a cricketer catches a fast-moving cricket ball, they gradually pull their hand backward. This action reduces the impact of catching the ball due to which principle?
a) Newton’s First Law of Motion
b) Newton’s Second Law of Motion
c) Newton’s Third Law of Motion
d) The principle of conservation of momentum
Answer: b) Newton’s Second Law of Motion
Explanation: By pulling the hand backward, the cricketer increases the time taken for the ball’s momentum to change, thereby reducing the force exerted on the hand according to Newton’s Second Law of Motion (F = ma).
Q6. What does the Third Law of Motion state?
a) Force equals mass times acceleration
b) Every action has an equal and opposite reaction
c) The rate of change of momentum is directly proportional to the imposed force
d) Objects at rest stay at rest unless acted upon by a force
Answer: b) Every action has an equal and opposite reaction
Explanation: 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, and when one object exerts a force on another, the second object exerts an equal and opposite force on the first.
Q7. What is the SI unit of force?
a) Kilogram (kg)
b) Meter per second squared (m/s²)
c) Newton (N)
d) Joule (J)
Answer: c) Newton (N)
Explanation: The SI unit of force is the Newton (N), defined as the force that gives a mass of one kilogram an acceleration of one meter per second squared.
Q8. When a ball rolls down an inclined plane, its velocity:
a) Decreases due to gravity
b) Remains constant
c) Increases due to the force of gravity
d) Instantly becomes zero
Answer: c) Increases due to the force of gravity
Explanation: When a ball rolls down an inclined plane, its velocity increases due to the acceleration caused by the force of gravity acting on it.
Q9. Which of the following is a consequence of inertia?
a) A person standing in a bus falls backward when the bus starts moving suddenly.
b) An object will continue moving at a constant velocity unless an external force acts on it.
c) A cricket ball hits harder than a tennis ball when thrown with the same force.
d) Both a) and b) are correct.
Answer: d) Both a) and b) are correct.
Explanation: Inertia is the tendency of an object to resist changes in its state of motion. A person falling backward in a moving bus and an object continuing its motion at a constant velocity unless acted upon by an external force are both consequences of inertia.
Q10. Friction always acts:
a) In the direction of motion of the object.
b) Opposite to the direction of motion of the object.
c) Perpendicular to the direction of motion.
d) In the same direction as the applied force.
Answer: b) Opposite to the direction of motion of the object.
Explanation: Friction is a force that opposes the relative motion or tendency of such motion between two surfaces in contact. It acts opposite to the direction of motion.
Q11. A force can change:
a) The shape of an object.
b) The speed of an object.
c) The direction of motion of an object.
d) All of the above.
Answer: d) All of the above.
Explanation: A force can bring various changes to an object: it can change the shape and size of the object, alter the speed, and change the direction of its motion.
Q12. The tendency of a moving object to continue in a straight line or a stationary object to remain in place is known as:
a) Momentum
b) Inertia
c) Acceleration
d) Velocity
Answer: b) Inertia
Explanation: Inertia is the property of an object by virtue of which it cannot change its state of rest or uniform motion along a straight line on its own.
Q13. When a bullet is fired from a gun, the gun recoils. This is an example of:
a) Newton’s First Law of Motion
b) Newton’s Second Law of Motion
c) Newton’s Third Law of Motion
d) The principle of conservation of momentum
Answer: c) Newton’s Third Law of Motion
Explanation: The recoil of a gun when a bullet is fired is an example of Newton’s Third Law of Motion, which states that for every action, there is an equal and opposite reaction.
Q14. The mass of an object is a measure of its:
a) Weight
b) Volume
c) Density
d) Inertia
Answer: d) Inertia
Explanation: The mass of an object is a measure of its inertia, which is the resistance to a change in its state of motion or rest.
Q15. If a car increases its velocity from 20 m/s to 40 m/s in 5 seconds, its acceleration is:
a) 4 m/s²
b) 20 m/s²
c) 8 m/s²
d) 10 m/s²
Answer: a) 4 m/s²
Explanation: Acceleration is the rate of change of velocity. It is calculated as the change in velocity divided by the time taken. Here, acceleration = (final velocity – initial velocity) / time = (40 m/s – 20 m/s) / 5 s = 4 m/s².
Q16. When two objects, one light and one heavy, are both pushed with the same force for the same amount of time, which one will have a greater acceleration?
a) The light object
b) The heavy object
c) Both will have the same acceleration
d) Cannot be determined
Answer: a) The light object
Explanation: According to Newton’s Second Law of Motion, the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass (a = F/m). Therefore, if the same force is applied to two objects of different masses for the same duration, the lighter object will experience a greater acceleration. This is because the same force will cause a larger change in motion for the object with less mass.
Q17. What is the unit of measurement for momentum?
a) Newton (N)
b) Kilogram meter per second (kg m/s)
c) Joule (J)
d) Meter per second squared (m/s²)
Answer: b) Kilogram meter per second (kg m/s)
Explanation: Momentum is measured in kilogram meter per second (kg m/s). It is the product of the mass of an object and its velocity.
Q18. A force acting on a body for a given time changes its:
a) Inertia
b) Mass
c) Momentum
d) Color
Answer: c) Momentum
Explanation: When a force acts on a body for a certain duration, it changes the body’s momentum. This is in accordance with Newton’s Second Law of Motion, which relates force, mass, acceleration, and change in momentum.
Q19. When a car suddenly stops, passengers are pushed forward due to:
a) Gravity
b) Momentum
c) External force
d) Inertia
Answer: d) Inertia
Explanation: When a car suddenly stops, the passengers are pushed forward due to inertia, which is the tendency of the body to continue its state of motion. The car stops, but the passengers tend to continue moving forward.
Q20. The momentum of an object is the product of:
a) Its mass and velocity
b) Its mass and acceleration
c) Its force and displacement
d) Its velocity and acceleration
Answer: a) Its mass and velocity
Explanation: Momentum is defined as the product of the mass and velocity of an object. It is a vector quantity, having both magnitude and direction.
Q21. If the mass of an object is doubled while its velocity remains constant, its momentum will:
a) Double
b) Halve
c) Remain the same
d) Quadruple
Answer: a) Double
Explanation: Momentum is directly proportional to the mass of an object. If the mass is doubled while the velocity remains constant, the momentum will also double.
Q22. When two bodies of different masses are freely falling under gravity, they reach the ground:
a) At different times
b) Simultaneously
c) With different speeds
d) With the same kinetic energy
Answer: b) Simultaneously
Explanation: When two bodies of different masses are freely falling under gravity, and air resistance is negligible, they reach the ground simultaneously. This is because the acceleration due to gravity is the same for all objects irrespective of their masses.
Q23. Which of the following is an example of Newton’s Third Law of Motion?
a) A ball rolling down a hill
b) A rocket launching into space
c) A person walking on a flat surface
d) A book lying on a table
Answer: b) A rocket launching into space
Explanation: A rocket launching into space is an example of Newton’s Third Law of Motion. The rocket expels gas downwards (action), and the gas exerts an equal and opposite force upwards on the rocket (reaction), propelling it forward.
Q24. Which of the following factors does not affect frictional force?
a) The materials of the surfaces in contact
b) The weight of the object
c) The area of contact between the surfaces
d) The color of the surfaces
Answer: d) The color of the surfaces
Explanation: Frictional force is affected by the nature of the surfaces in contact, the weight or normal force, and the area of contact. However, the color of the surfaces does not have any effect on the frictional force.
Q25. The rate of change of velocity is known as:
a) Speed
b) Momentum
c) Acceleration
d) Force
Answer: c) Acceleration
Explanation: Acceleration is defined as the rate at which an object changes its velocity. It is a vector quantity and involves a change in either the magnitude or direction of velocity.
Q26. If the velocity of an object doubles, what happens to its kinetic energy?
a) It remains the same
b) It doubles
c) It quadruples
d) It halves
Answer: c) It quadruples
Explanation: Kinetic energy is given by the formula
1
2
2
2
1
mv
2
. If the velocity of an object is doubled, its kinetic energy becomes four times greater, as kinetic energy is proportional to the square of the velocity.
Q27. What will be the effect on the weight of an object if the acceleration due to gravity doubles?
a) It will remain the same
b) It will become half
c) It will double
d) It will become four times
Answer: c) It will double
Explanation: Weight is the force with which an object is attracted towards the earth, given by the product of mass and acceleration due to gravity (W = mg). If the acceleration due to gravity doubles, the weight of the object will also double.
Q28. A force can be defined as:
a) A push or pull
b) A source of energy
c) A measure of inertia
d) A type of velocity
Answer: a) A push or pull
Explanation: A force is defined as a push or pull that has the ability to change the state of motion of an object. It can change the speed, direction, shape, or size of the object.
Q29. What is the momentum of a stationary object?
a) Infinity
b) Constant
c) Zero
d) Depends on the mass
Answer: c) Zero
Explanation: For a stationary object, the velocity is zero. Since momentum is the product of mass and velocity, the momentum of a stationary object is also zero.
Q30. When a rubber ball is dropped, it bounces back. This is an example of:
a) Newton’s First Law of Motion
b) Newton’s Second Law of Motion
c) Newton’s Third Law of Motion
d) The principle of conservation of energy
Answer: c) Newton’s Third Law of Motion
Explanation: When a rubber ball is dropped and it bounces back, it exemplifies Newton’s Third Law of Motion. The ball exerts a force on the ground upon impact, and the ground exerts an equal and opposite force on the ball, causing it to bounce back.
Q31. Which of the following is the correct representation of Newton’s Second Law of Motion?
a) F = m/a
b) F = ma
c) F = a/m
d) F = m + a
Answer: b) F = ma
Explanation: Newton’s Second Law of Motion states that the force acting on an object is equal to the mass of that object multiplied by its acceleration. This is represented by the equation F = ma.
Q32. The force required to keep an object moving with the same speed in a circular path is called:
a) Gravitational force
b) Frictional force
c) Centripetal force
d) Inertial force
Answer: c) Centripetal force
Explanation: Centripetal force is the force that is required to keep an object moving in a circular path. It acts towards the center of the circle and is essential for maintaining circular motion.
Q33. Which of the following scenarios is an example of balanced forces?
a) A car accelerating on a highway
b) A book resting on a table
c) A ball rolling down a hill
d) A rocket launching into space
Answer: b) A book resting on a table
Explanation: Balanced forces are when two forces acting in opposite directions on an object, and are equal in size. A book resting on a table is an example of this, as the gravitational force pulling it downwards is balanced by the support force of the table pushing it upwards.
Q34. The tendency of objects to resist any change in their state of motion is described by:
a) Newton’s Second Law of Motion
b) Newton’s First Law of Motion
c) The Law of Universal Gravitation
d) The Law of Conservation of Energy
Answer: b) Newton’s First Law of Motion
Explanation: Newton’s First Law of Motion, also known as the Law of Inertia, describes the tendency of objects to resist any change in their state of motion. An object at rest stays at rest, and an object in motion stays in motion with the same speed and direction unless acted upon by an unbalanced force.
Q35. The gravitational force between two objects depends on:
a) The distance between the objects and the sum of their masses
b) The distance between the objects and the product of their masses
c) Only the mass of the heavier object
d) Only the distance between the two objects
Answer: b) The distance between the objects and the product of their masses
Explanation: The gravitational force between two objects depends on the product of their masses and inversely on the square of the distance between their centers. This is described by Newton’s Law of Universal Gravitation.
Q36. If a force acts perpendicular to the direction of motion of an object, what effect does it have?
a) It causes the object to accelerate
b) It causes the object to decelerate
c) It changes the shape of the object
d) It changes the direction of motion of the object
Answer: d) It changes the direction of motion of the object
Explanation: When a force acts perpendicular to the direction of motion, it causes a change in the direction of motion of the object, without necessarily changing its speed.
Q37. Which of the following is not a force?
a) Friction
b) Gravity
c) Mass
d) Tension
Answer: c) Mass
Explanation: Mass is not a force; it is a property of matter that measures its resistance to acceleration. Friction, gravity, and tension are all examples of forces.
Q38. If two objects have the same mass, but different velocities, which one has the greater momentum?
a) The object with the smaller velocity
b) The object with the greater velocity
c) Both have the same momentum
d) Impossible to determine without knowing the exact velocities
Answer: b) The object with the greater velocity
Explanation: Momentum is the product of mass and velocity. If two objects have the same mass but different velocities, the object with the greater velocity will have the greater momentum.
Q39. In the absence of air resistance, how does the speed of a freely falling object change with time?
a) It decreases
b) It remains constant
c) It increases
d) It fluctuates
Answer: c) It increases
Explanation: In the absence of air resistance, the speed of a freely falling object increases with time due to the constant acceleration caused by gravity.
Q40. Which of the following is a unit of acceleration?
a) Newton
b) Kilogram
c) Meter per second squared (m/s²)
d) Joule
Answer: c) Meter per second squared (m/s²)
Explanation: Acceleration is measured in meters per second squared (m/s²). It is the rate of change of velocity per unit of time.
Q41. What force is responsible for keeping a satellite in orbit around a planet?
a) Centrifugal force
b) Centripetal force
c) Gravitational force
d) Magnetic force
Answer: b) Centripetal force
Explanation: The centripetal force, which is provided by the planet’s gravitational pull, is responsible for keeping a satellite in orbit. This force acts towards the center of the orbit, keeping the satellite in a circular path around the planet.
Q42. When a bus suddenly moves forward, passengers tend to fall backward. This is due to:
a) Gravitational force
b) Frictional force
c) Centrifugal force
d) Inertia
Answer: d) Inertia
Explanation: This phenomenon is due to inertia, which is the tendency of an object to resist a change in its state of motion. The lower part of the body moves forward with the bus, while the upper part tries to remain in its initial state of rest, resulting in passengers falling backward.
Q43. What happens to the acceleration of an object if the net external force acting on it is halved?
a) It remains the same
b) It is doubled
c) It is halved
d) It becomes zero
Answer: c) It is halved
Explanation: According to Newton’s Second Law of Motion (F = ma), if the net external force is halved while the mass remains constant, the acceleration is also halved.
Q44. The tendency of a stationary or moving object to resist any change in its state of motion is attributed to its:
a) Mass
b) Volume
c) Weight
d) Inertia
Answer: d) Inertia
Explanation: Inertia is the property of an object by virtue of which it resists any change in its state of rest or uniform motion. It is directly related to the mass of the object, but it is the inertia itself that is the property being described.
Q45. When a force is applied at one end of an object and the other end is fixed, the object tends to:
a) Move in the direction of the force
b) Change its shape
c) Increase its mass
d) Decrease its volume
Answer: b) Change its shape
Explanation: When a force is applied at one end of an object while the other end is fixed, the object tends to change its shape due to the stress applied.
Q46. Which law explains why we need to wear seat belts in a car?
a) Newton’s First Law of Motion
b) Newton’s Second Law of Motion
c) Newton’s Third Law of Motion
d) The Law of Conservation of Momentum
Answer: a) Newton’s First Law of Motion
Explanation: Newton’s First Law of Motion, or the Law of Inertia, explains why seat belts are necessary. In a car crash or sudden stop, the seat belt provides the unbalanced force that changes the motion of the passenger, preventing them from continuing forward due to inertia.
Q47. The product of mass and velocity of an object is known as its:
a) Acceleration
b) Momentum
c) Energy
d) Force
Answer: b) Momentum
Explanation: Momentum is defined as the product of the mass and velocity of an object. It is a vector quantity, having both magnitude and direction.
Q48. A ball is thrown vertically upwards. What is the velocity of the ball at its highest point?
a) Maximum
b) Zero
c) Constant
d) Accelerating
Answer: b) Zero
Explanation: At the highest point of its trajectory, the velocity of the ball is zero. This is the point where the ball changes its direction from upward to downward and momentarily stops before descending.
Q49. Which of the following is true about the acceleration due to gravity?
a) It decreases with an increase in altitude from the Earth’s surface.
b) It increases with an increase in altitude from the Earth’s surface.
c) It remains constant regardless of altitude.
d) It is greater at the equator than at the poles.
Answer: a) It decreases with an increase in altitude from the Earth’s surface.
Explanation: The acceleration due to gravity decreases as the altitude increases from the Earth’s surface. This is because gravitational force weakens with distance from the Earth’s center.
Q50. What is the main cause of friction?
a) The smoothness of surface
b) The roughness of surface
c) The mass of the object
d) The shape of the object
Answer: b) The roughness of surface
Explanation: Friction primarily arises due to the irregularities or roughness on the surfaces in contact. Even surfaces that appear smooth have microscopic irregularities that interlock and create resistance to motion.
Q51. A moving object does not need a force to keep moving. This statement is:
a) True, according to Newton’s First Law of Motion
b) False, as all objects need a force to keep moving
c) True, only in space
d) False, as per the law of inertia
Answer: a) True, according to Newton’s First Law of Motion
Explanation: According to Newton’s First Law of Motion, an object in motion continues to stay in motion at a constant velocity unless acted upon by an unbalanced external force. This principle demonstrates the concept of inertia.
Q52. Which factor does not affect the kinetic energy of an object?
a) Its mass
b) Its velocity
c) Its color
d) Its shape
Answer: c) Its color
Explanation: The kinetic energy of an object depends on its mass and velocity (KE = 1/2 mv²) and is not influenced by factors like color or shape.
Q53. What happens to the kinetic energy of a car when its speed is tripled?
a) It remains the same
b) It triples
c) It increases nine times
d) It doubles
Answer: c) It increases nine times
Explanation: Kinetic energy is proportional to the square of the velocity (KE = 1/2 mv²). If the speed is tripled, the kinetic energy increases by a factor of nine (3² = 9).
Q54. An object moves with a constant speed in a circular path. What can we say about the forces acting on it?
a) No forces are acting on it
b) There is a net force acting towards the center of the path
c) There is a net force acting in the direction of motion
d) The forces are balanced and it is in equilibrium
Answer: b) There is a net force acting towards the center of the path
Explanation: For an object moving with constant speed in a circular path, a net centripetal force acts towards the center of the circular path. This force is responsible for changing the direction of the object’s velocity and keeping it in circular motion.
Q55. If the net force acting on an object is zero, then the object:
a) Must be at rest
b) Must be moving with a constant velocity
c) Must be accelerating
d) Can either be at rest or moving with a constant velocity
Answer: d) Can either be at rest or moving with a constant velocity
Explanation: According to Newton’s First Law of Motion, if the net force acting on an object is zero, the object will either remain at rest or continue moving at a constant velocity. This is a state of equilibrium.
Q56. When a carpet is beaten with a stick, dust comes out. This can be explained by:
a) Newton’s First Law of Motion
b) Newton’s Second Law of Motion
c) Newton’s Third Law of Motion
d) The Law of Conservation of Momentum
Answer: a) Newton’s First Law of Motion
Explanation: When a carpet is beaten, it quickly moves, but the dust particles tend to stay in their state of rest (inertia). This is an example of Newton’s First Law of Motion, where the inertia of the dust particles causes them to separate from the carpet.
Q57. When two forces act in the opposite directions on an object, the net force acting on it is:
a) The sum of the two forces
b) Zero
c) The difference between the two forces
d) The product of the two forces
Answer: c) The difference between the two forces
Explanation: When two forces act in opposite directions, the net force is the difference between the magnitudes of the two forces. The direction of the net force is the same as that of the larger force.
Q58. Which of the following statements is true about mass and weight?
a) Mass and weight are the same.
b) Mass is a measure of how much matter an object has, while weight is the force of gravity on an object.
c) Mass changes with location, while weight remains constant.
d) Weight is a measure of how much matter an object has, while mass is the force of gravity on an object.
Answer: b) Mass is a measure of how much matter an object has, while weight is the force of gravity on an object.
Explanation: Mass is a property of an object that reflects the amount of matter in it, and it remains constant regardless of location. Weight, on the other hand, is the force exerted by gravity on an object and varies with the strength of the gravitational field.
Q59. What does the slope of a speed-time graph indicate?
a) Acceleration
b) Velocity
c) Distance
d) Force
Answer: a) Acceleration
Explanation: The slope of a speed-time (or velocity-time) graph represents the acceleration of an object. It is calculated as the change in velocity over time.
Q60. The SI unit of momentum is:
a) Kilogram meter (kg·m)
b) Kilogram meter per second (kg·m/s)
c) Newton second (N·s)
d) Meter per second squared (m/s²)
Answer: b) Kilogram meter per second (kg·m/s)
Explanation: The SI unit of momentum is kilogram meter per second (kg·m/s). Momentum is defined as the product of mass (in kilograms) and velocity (in meters per second).
Q61. A force that opposes the relative motion of two surfaces in contact is known as:
a) Tension
b) Normal force
c) Friction
d) Gravitational force
Answer: c) Friction
Explanation: Friction is the force that opposes the relative motion or tendency of such motion between two surfaces that are in contact with each other.
Q62. Which of the following is not a vector quantity?
a) Velocity
b) Force
c) Mass
d) Acceleration
Answer: c) Mass
Explanation: Mass is a scalar quantity as it has only magnitude and no direction. Velocity, force, and acceleration are all vector quantities as they have both magnitude and direction.
Q63. When a force is applied on a soft object, the object tends to:
a) Increase its mass
b) Decrease its velocity
c) Change its shape
d) Increase its acceleration
Answer: c) Change its shape
Explanation: When a force is applied to a soft object, it tends to deform or change its shape. The change in shape is due to the object’s inability to resist the force.
Q64. If an object is moving at a constant velocity, the net force acting on it must be:
a) Increasing
b) Decreasing
c) Zero
d) Constant but not zero
Answer: c) Zero
Explanation: According to Newton’s First Law of Motion, if an object is moving with a constant velocity, the net external force acting on it must be zero. This implies that the object is in a state of equilibrium.