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📘 Study MCQs
Q1. The natural property of an object that causes it to resist any change in its state of rest or uniform motion is called:
• Velocity
• Acceleration
• Inertia
• Momentum
Answer: Inertia
Imagine trying to push a heavy crate from rest. It resists your push. Once moving, it’s hard to stop. This inherent resistance to changes in motion—whether starting, stopping, or turning—is not a force, but a property of all matter called inertia. The more mass an object has, the greater its inertia.
Q2. Newton’s First Law of Motion is fundamentally a statement about:
• The relationship between force and acceleration
• The conservation of energy
• The property of inertia in objects
• The nature of gravitational force
Answer: The property of inertia in objects
Newton’s First Law states: “An object at rest stays at rest, and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.” This describes how objects behave due to their inertia—their tendency to maintain their current state of motion.
Q3. When a moving car suddenly brakes, passengers lurch forward because:
• The seat pushes them forward
• Their bodies continue moving forward due to inertia
• Air pressure inside the car increases
• Gravity suddenly decreases
Answer: Their bodies continue moving forward due to inertia
The car and passengers are both moving forward. When brakes apply force to stop the car, that force acts directly on the car. The passengers’ bodies, due to inertia, tend to continue moving forward at the original speed. Since no immediate force stops their bodies, they lurch forward relative to the suddenly slowing car.
Q4. Seat belts in vehicles are primarily designed to:
• Increase the comfort of the ride
• Provide a stylish appearance
• Prevent passengers from being thrown forward during sudden stops
• Help passengers exit the vehicle quickly
Answer: Prevent passengers from being thrown forward during sudden stops
During sudden braking, inertia causes passengers to continue moving forward. Seat belts apply a restraining force, increasing the time it takes for the passenger to stop. This reduces the average stopping force on the body (as force = change in momentum/time), preventing them from hitting the dashboard and minimizing injury.
Q5. When a stationary bus starts moving abruptly, standing passengers tend to fall backward because:
• Air pushes them backward
• The bus floor moves forward under their feet
• Their upper bodies tend to remain at rest due to inertia
• Gravity increases momentarily
Answer: Their upper bodies tend to remain at rest due to inertia
Initially, the entire passenger is at rest. When the bus starts, the force acts on the bus, which acts on the passengers’ feet through the floor. The feet begin moving forward, but the upper body, due to inertia, tends to remain at rest. This causes the person to lean or fall backward relative to the bus.
Q6. During a sharp turn at high speed in a car, passengers feel pushed toward the outside of the turn because:
• Centrifugal force pushes them outward
• They continue moving in a straight line due to inertia
• The car door pulls them outward
• Gravity decreases during turns
Answer: They continue moving in a straight line due to inertia
Objects in motion tend to continue in a straight line (inertia). When the car turns, it changes direction. The passengers’ bodies, however, tend to continue straight ahead. Relative to the turning car, it feels as if they are being pushed toward the outside of the curve. This is actually inertia, not an outward force.
Q7. A change in the direction of a moving object, such as a car turning a corner, requires:
• No force at all
• A balanced force system
• An unbalanced net force
• Only a decrease in speed
Answer: An unbalanced net force
A change in direction is a change in velocity, which is acceleration. According to Newton’s Second Law, acceleration requires a net force. For a car to turn, friction between the tires and road provides an unbalanced centripetal (center-seeking) force that pulls the car inward, changing its direction.
Q8. Compared to a bicycle, a loaded truck is much harder to stop once moving because the truck has:
• Better brakes
• More wheels
• Greater inertia due to larger mass
• Less friction with the road
Answer: Greater inertia due to larger mass
Inertia is directly proportional to mass. A loaded truck has significantly more mass than a bicycle. This greater inertia means the truck strongly resists changes to its state of motion. It requires a much larger force (from powerful brakes applied over a longer distance) to overcome its inertia and bring it to a stop.
Q9. The quantitative measure of an object’s inertia is its:
• Volume
• Weight
• Mass
• Density
Answer: Mass
Inertia is the qualitative concept of resistance to change in motion. Mass is the quantitative, measurable property that tells us how much inertia an object has. A 10 kg object has twice the inertia of a 5 kg object. Mass is measured in kilograms (kg) and is distinct from weight, which is a force.
Q10. Leaves fall from a tree when its branches are shaken vigorously because:
• Wind is created by the shaking
• The leaves are tired of being on the tree
• The leaves’ inertia keeps them at rest while branches move
• Gravity increases during shaking
Answer: The leaves’ inertia keeps them at rest while branches move
The leaves are initially at rest on the branches. When you shake the branches, you apply force to them, making them move. The leaves, due to their inertia, tend to remain where they are. As the branches move away from the stationary leaves, the connection breaks, and gravity pulls the leaves down.
Q11. In the context of motion, mass can be defined as:
• The amount of space an object occupies
• The force of gravity on an object
• A measure of the quantity of matter and its inertia
• The volume multiplied by density
Answer: A measure of the quantity of matter and its inertia
Mass has two fundamental aspects. First, it measures the amount of matter (number and type of atoms) in an object. Second, and crucially for dynamics, it measures the object’s inertia—its resistance to acceleration when a force is applied. This is why ‘m’ appears in Newton’s Second Law: F = m × a.
Q12. According to Galileo’s thought experiments with inclined planes, an object moving on a perfectly smooth, horizontal surface would:
• Slow down and stop quickly
• Speed up continuously
• Move forever with constant speed
• Oscillate back and forth
Answer: Move forever with constant speed
Galileo reasoned that if a ball rolled down one incline and up another, it nearly reached its original height. He imagined making the second incline less steep—the ball would roll farther to reach that height. Extending this to a perfectly horizontal, frictionless plane, the ball would never reach its original height, so it would keep rolling forever at constant speed.
Q13. The famous scientist who built upon Galileo’s ideas and formulated the Three Laws of Motion was:
• Albert Einstein
• Michael Faraday
• Isaac Newton
• Archimedes
Answer: Isaac Newton
While Galileo pioneered the concepts of inertia and relative motion through experiments, it was Sir Isaac Newton who, in his 1687 work “Philosophiæ Naturalis Principia Mathematica,” formally stated the three universal laws of motion that became the foundation of classical mechanics.
Q14. If the net force acting on an object is zero, the object must be:
• At rest
• Moving with constant velocity
• Either at rest or moving with constant velocity
• Accelerating
Answer: Either at rest or moving with constant velocity
Newton’s First Law states that if the net force is zero, there is no acceleration. This means the velocity does not change. The object could be stationary (velocity = 0) or moving in a straight line at a constant speed. Both are states of constant velocity (zero is a constant value).
Q15. When a goalkeeper kicks a stationary football, the force applied primarily changes the ball’s:
• Mass
• Colour
• Shape permanently
• Velocity
Answer: Velocity
The kick applies an unbalanced force to the ball. According to Newton’s Second Law, this force causes acceleration. The ball accelerates from rest (velocity = 0) to a certain speed in a certain direction. Thus, the force changes the ball’s state of motion—its velocity.
Q16. When a football is passed between players, what changes each time it is kicked?
• Its mass
• Its chemical composition
• Its velocity
• Its temperature significantly
Answer: Its velocity
Each kick applies a new force to the ball. A force causes acceleration, which is a change in velocity. The kick might increase its speed, decrease it, or change its direction entirely. So, with each interaction (kick, header, save), the ball’s velocity vector changes.
Q17. Galileo’s use of inclined planes in his experiments was crucial because they:
• Eliminated gravity
• Made objects fall faster
• Slowed down motion enough to be measurable
• Increased the mass of rolling objects
Answer: Slowed down motion enough to be measurable
Free-falling objects move too quickly to study with the timing methods available in Galileo’s time (like water clocks or his own pulse). By rolling balls down gentle inclines, he “diluted” the effect of gravity, producing slower, measurable motion from which he could deduce the laws governing all accelerated motion.
Q18. Galileo’s astronomical observations with his improved telescope supported the idea that:
• The Earth is stationary at the center of the universe
• The Moon has a smooth, perfect surface
• The Sun and planets orbit the Earth
• Celestial bodies are not perfect and unchanging, and Jupiter has moons
Answer: Celestial bodies are not perfect and unchanging, and Jupiter has moons
Galileo saw mountains on the Moon (not a perfect sphere), spots on the Sun (not unchanging), and four moons orbiting Jupiter (a mini solar system). These observations challenged the prevailing Aristotelian/Ptolemaic view of perfect, unchanging heavens with Earth at the center, supporting the Copernican model.
Q19. The statement “all objects fall at the same rate regardless of mass (ignoring air resistance)” is a conclusion associated with:
• Aristotle
• Galileo
• Newton
• Einstein
Answer: Galileo
Aristotle believed heavier objects fall faster. Galileo, through thought experiments and likely the Leaning Tower of Pisa experiment, argued that if you drop two objects of different mass, they should fall at the same rate. He correctly identified that gravity gives all objects the same acceleration (g), a concept Newton later explained with his law of gravitation.
Q20. A key difference between mass and weight is that:
• Mass is a force, weight is not
• Weight depends on location (like on the Moon), mass does not
• They are the same thing expressed in different units
• Mass changes with gravity, weight is constant
Answer: Weight depends on location (like on the Moon), mass does not
Mass (in kg) is the amount of matter and a measure of inertia. It is constant everywhere. Weight (in Newtons) is the force of gravity on that mass (W = m*g). Since ‘g’ (acceleration due to gravity) is less on the Moon, your weight would be less there, but your mass remains the same.
Q21. In a head-on collision between a small car and a large truck, the car usually experiences greater damage because:
• The car is less colourful
• The truck has more inertia
• The car’s driver is less skilled
• The truck’s brakes are better
Answer: The truck has more inertia
The truck has much greater mass, and therefore much greater inertia. It strongly resists changes to its motion. During the collision, the car experiences a massive force trying to change the truck’s motion, causing severe deformation. The truck, due to its large inertia, experiences a relatively smaller change in its motion.
Q22. When you shake a bottle of ketchup to get the ketchup out, you are using the principle of:
• Gravity only
• Inertia
• Magnetic attraction
• Chemical reaction
Answer: Inertia
You start the bottle moving downward then suddenly stop it. The thick ketchup inside, due to its inertia, tends to continue moving downward when the bottle stops. This relative motion helps dislodge the ketchup from the neck of the bottle, making it flow out.
Q23. If you jump straight up inside a smoothly moving train, you will land:
• Further back in the train
• Further forward in the train
• At the exact same spot
• It depends on the train’s speed
Answer: At the exact same spot
While in the air, you continue moving forward with the same horizontal velocity as the train (due to your inertia). The train also moves forward at the same speed. Since you and the train maintain the same horizontal motion, you land back on the same spot relative to the train floor.
Q24. The design of a hammer head being heavy is related to:
• Making it look strong
• Increasing its inertia for more effective striking
• Reducing its cost
• Making it float in water
Answer: Increasing its inertia for more effective striking
A heavy head has large mass, hence large inertia. When you swing the hammer, this inertia makes the head resist slowing down. When it hits a nail, it transfers a large amount of momentum over a short time, delivering a strong impulse (force × time) that drives the nail effectively.
Q25. Why do athletes run a few steps before taking a long jump?
• To build up speed and momentum
• To follow competition rules
• To reduce their mass
• To decrease friction
Answer: To build up speed and momentum
By running, the athlete gains horizontal velocity and therefore horizontal momentum (mass × velocity). Due to inertia, this horizontal motion continues even after they jump. This allows them to travel further horizontally while in the air, contributing significantly to the length of the jump.
Q26. The discomfort felt when an elevator starts moving upward is due to:
• A decrease in gravity
• An increase in air pressure
• Your inertia resisting the new upward acceleration
• The elevator floor pushing down
Answer: Your inertia resisting the new upward acceleration
Initially, you are at rest. When the elevator accelerates upward, the floor pushes on your feet, giving your whole body an upward acceleration. Your body’s inertia resists this sudden change from rest to upward motion, making you feel momentarily heavier or “pressed” into the floor.
Q27. A satellite in orbit around Earth continues to move without an engine constantly firing because:
• There is no gravity in space
• Its inertia carries it forward while gravity bends its path
• It is beyond Earth’s gravitational pull
• Space has a natural pushing force
Answer: Its inertia carries it forward while gravity bends its path
The satellite has tangential velocity (sideways speed) due to its launch. Inertia would make it travel in a straight line into space. However, Earth’s gravity acts as an unbalanced centripetal force, constantly pulling it inward. This combination of forward inertia and inward gravitational pull results in a curved orbital path.
Q28. When a magician pulls a tablecloth out from under dishes without breaking them, it demonstrates:
• The cloth has very low friction
• The dishes have low inertia
• The dishes’ inertia keeps them nearly stationary if the cloth is pulled quickly
• The cloth is specially treated
Answer: The dishes’ inertia keeps them nearly stationary if the cloth is pulled quickly
The force of friction between the cloth and dishes acts over a very short time if the cloth is jerked quickly. The dishes, due to their inertia, tend to remain at rest. The impulsive force isn’t enough to give them significant horizontal velocity before the cloth is removed, so they settle back down nearly in place.
Q29. The concept that helped move science away from the idea that “a force is needed to maintain motion” was:
• Relativity
• Inertia
• Gravitation
• Friction
Answer: Inertia
Before Galileo and Newton, it was thought a constant force was needed to keep an object moving. The concept of inertia explains that an object in motion will naturally continue in motion. The force is only needed to overcome opposing forces like friction or to change the motion. This was a revolutionary shift in thinking.
Q30. If you are in a spaceship far from any stars or planets, and you turn off all engines, the spaceship will:
• Slow down and eventually stop
• Continue moving at constant velocity
• Start spinning randomly
• Fall toward the nearest large object
Answer: Continue moving at constant velocity
In the near-vacuum of space, friction is almost zero. With engines off, no net external force acts on the ship. According to Newton’s First Law (inertia), it will continue moving in a straight line at whatever constant speed it had when the engines were turned off.