Q.Which of the following is NOT the factor affecting projectile trajectory?
(a) Gravity
(b) Angle of Release
(c) Buoyant Force
(d) Air Resistance
CBSECBSE Class XII Board 2023MCQ· 1mImportance★★★★★
✓ Free question
Concept understanding — Center Of Gravity Balance
The Intuition: The One Point That Holds Everything Together
Think about balancing a pencil on your finger. You slide it back and forth until you find that one spot where it stays perfectly horizontal. That spot isn't random — it's the point where the pencil's weight on the left exactly cancels the weight on the right. If you put your finger anywhere else, the pencil tips.
Now imagine a much more complicated object: a chair, a cricket bat, or even your own body. Every tiny piece of that object is pulled downward by gravity. The center of gravity is the single point where you could pretend all that weight is concentrated. If you support the object exactly at that point, it balances perfectly — no tipping, no rotation.
Note
For most objects on Earth, the center of gravity is the same as the center of mass. The distinction matters only when gravity varies significantly across the object (e.g., a very tall building), which you won't see in school-level problems.
The Precise Statement
The center of gravity of an object is the point at which the entire weight of the object can be considered to act, for the purpose of analyzing translational and rotational equilibrium under gravity.
Mathematically, for a system of particles with weights w1,w2,…,wn located at positions (x1,y1,z1),…,(xn,yn,zn), the coordinates of the center of gravity are:
The center of gravity is the key to stability. An object is stable if its center of gravity lies above its base of support. That's why a cone standing on its base is stable, but balanced on its tip it falls — the center of gravity is above the tiny tip, and any nudge moves it outside the base.
Tip
To find the center of gravity of an irregular flat object, hang it from two different points. Draw vertical lines downward from each suspension point. The center of gravity is where those lines cross.
A Common Mistake
Students often think the center of gravity must be inside the object. It doesn't have to be. A ring's center of gravity is at its geometric center — empty space. A boomerang's center of gravity lies outside its material. The definition is about where the weight acts, not where the matter is.
The Core Idea
The center of gravity is the balance point. Every object, no matter how weirdly shaped, has exactly one such point. Find it, and you can predict how the object will behave under gravity — whether it stands, tips, or spins.
Projectile trajectory in sports is shaped by gravity, the angle and velocity of release, and air resistance — not buoyant force, which is a fluid (liquid/water) phenomenon, not something that acts on a ball moving through air in a normal sporting context.
✓Final answer
(c) Buoyant Force — it is not one of the recognised factors affecting projectile trajectory in sport.
Buoyant force is the odd one out — projectile trajectory in sport is governed by gravity, angle of release and air resistance, not buoyancy.
A projectile — a javelin, shot, discus, or a ball in flight — follows a curved (parabolic) path determined by a specific, well-studied set of mechanical factors: the angle of release (an angle near 45° generally maximises range, though it varies with release height), the velocity/force of release, the height of release, the force of gravity pulling the object back down, and air resistance, which slows the projectile and can alter its path (especially relevant for light objects like a badminton shuttle or a discus). Buoyant force is the upward force a fluid exerts on a submerged or floating object — it explains why a boat floats or a swimmer feels lighter in water, but it plays no meaningful role in a projectile's flight through air in a track-and-field or ball-sport context.
Same / Similar Concept — real previous-year questions on the same or a closely similar concept, not this exact question.
CBSE 2023Set 75/EF1GH/41 markMCQ
Q.Which of the following is NOT the factor affecting projectile trajectory?
(a) Gravity
(b) Angle of Release
(c) Buoyant Force
(d) Air Resistance
›Reveal solutionSolution
Buoyant force is the odd one out — projectile trajectory in sport is governed by gravity, angle of release and air resistance, not buoyancy.
A projectile — a javelin, shot, discus, or a ball in flight — follows a curved (parabolic) path determined by a specific, well-studied set of mechanical factors: the angle of release (an angle near 45° generally maximises range, though it varies with release height), the velocity/force of release, the height of release, the force of gravity pulling the object back down, and air resistance, which slows the projectile and can alter its path (especially relevant for light objects like a badminton shuttle or a discus). Buoyant force is the upward force a fluid exerts on a submerged or floating object — it explains why a boat floats or a swimmer feels lighter in water, but it plays no meaningful role in a projectile's flight through air in a track-and-field or ball-sport context.