LESSON–3 : MOTION IN A PLANE
ADDITIONAL MATERIALS – 5
IIT JEE PREVIOUS YEAR QUESTIONS & ANSWERS (SET–3)
🔹 PYQ–1 (JEE ADVANCED – SPEED CONCEPT)
Question:
At what point during the projectile motion is the speed equal to
the horizontal component of velocity?
Answer:
At the highest point, because the vertical component of velocity becomes zero.
🔹 PYQ–2 (JEE MAIN – TIME LOGIC)
Question:
Two projectiles are projected simultaneously from the same point
with equal speeds at angles 30° and 60°.
Which one remains in air longer?
Answer:
Time of flight ∝ sinθ
Since sin60° > sin30°,
the projectile at 60° remains longer.
🔹 PYQ–3 (JEE ADVANCED – ENERGY VIEW)
Question:
Compare the magnitudes of velocities of a projectile at the
point of projection and at the point of landing (same level).
Answer:
Magnitudes are equal, because mechanical energy is conserved.
🔹 PYQ–4 (JEE ADVANCED – VECTOR SUBTRACTION)
Question:
Two particles move with velocities (6î + 8ĵ) m/s and (2î + 4ĵ) m/s.
Find the magnitude of relative velocity.
Answer:
vAB = (6−2)î + (8−4)ĵ = 4î + 4ĵ
|vAB| = √(4² + 4²) = 4√2 m/s
🔹 PYQ–5 (JEE MAIN – PROJECTILE HEIGHT)
Question:
A projectile is thrown with velocity 40 m/s at an angle of 30°.
Find the maximum height reached. (g = 10 m/s²)
Answer:
H = (u² sin²θ)/(2g)
= (1600 × 0.25)/20
= 20 m
🔹 PYQ–6 (JEE ADVANCED – LOGICAL)
Question:
Can the horizontal component of velocity of a projectile ever change
during its motion?
Answer:
No. In absence of air resistance, horizontal acceleration is zero, so horizontal velocity remains constant.
🔹 PYQ–7 (JEE MAIN – PERPENDICULAR VELOCITIES)
Question:
Two particles move perpendicular to each other with speeds
12 m/s and 5 m/s. Find their relative speed.
Answer:
Relative speed = √(12² + 5²) = √169 = 13 m/s
🔹 PYQ–8 (JEE ADVANCED – DIRECTION CHECK)
Question:
At which point is the velocity of a projectile perpendicular
to its acceleration?
Answer:
At the highest point of its trajectory.
🔹 PYQ–9 (JEE MAIN – VECTOR ANGLE)
Question:
Find the angle made by vector (5î + 12ĵ) with x-axis.
Answer:
tanθ = 12 / 5
θ ≈ 67.4°
🔹 PYQ–10 (JEE ADVANCED – CONCEPT TEST)
Question:
Is the acceleration of a projectile zero at the highest point?
Answer:
No. Acceleration is always equal to g and acts vertically downward.
🎯 HOW TO CRACK THESE PYQs (EXAM STRATEGY)
- Think in components, not whole velocity
- Use symmetry and conservation principles
- Draw vector diagram even for MCQs
- Do not assume acceleration becomes zero
- Check physical meaning before final answer
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