LESSON–3 : MOTION IN A PLANE

ADDITIONAL MATERIALS – 7
IIT JEE PREVIOUS YEAR QUESTIONS & ANSWERS (SET–5)

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🔹 PYQ–1 (JEE ADVANCED – VELOCITY DIRECTION)

Question:
At which point during projectile motion does the velocity vector make zero angle with the horizontal?

Answer:

At the highest point, because the vertical component of velocity becomes zero.

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🔹 PYQ–2 (JEE MAIN – SAME SPEED LOGIC)

Question:
A projectile is thrown upward at an angle. Compare the speed at launch and speed just before hitting the ground (at the same level).

Answer:

The speeds are equal, because mechanical energy is conserved.

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🔹 PYQ–3 (JEE ADVANCED – TIME VS PATH TRAP)

Question:
Two projectiles are projected with same speed. One is projected vertically upward and the other at an angle θ. Which one remains in air longer?

Answer:

The vertically projected body remains longer in air, because its vertical component of velocity is maximum.

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🔹 PYQ–4 (JEE ADVANCED – VECTOR CONCEPT)

Question:
Is it possible for the velocity and acceleration vectors of a projectile to be parallel at any point?

Answer:

No. Velocity is always tangential to the path, while acceleration is always vertically downward.

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🔹 PYQ–5 (JEE MAIN – RANGE LOGIC)

Question:
Two projectiles are projected with the same speed at angles 15° and 75°. Compare their ranges.

Answer:

Ranges are equal because sin(2 × 15°) = sin(2 × 75°) = sin30°.

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🔹 PYQ–6 (JEE ADVANCED – ZERO VELOCITY TRAP)

Question:
Can the velocity of a projectile ever become zero during its flight?

Answer:

No. At the highest point, only the vertical component becomes zero. Horizontal component always exists.

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🔹 PYQ–7 (JEE MAIN – RELATIVE VELOCITY THINKING)

Question:
Two cars move in perpendicular directions with speeds 16 m/s and 12 m/s. Find the magnitude of their relative velocity.

Answer:

Relative velocity = √(16² + 12²) = √400 = 20 m/s

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🔹 PYQ–8 (JEE ADVANCED – ACCELERATION CHECK)

Question:
At which point of the trajectory is the acceleration of a projectile minimum?

Answer:

Acceleration is constant (g) throughout the motion. It is never minimum or maximum.

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🔹 PYQ–9 (JEE MAIN – VECTOR ANGLE)

Question:
Find the angle between vectors (3î + 4ĵ) and (4î − 3ĵ).

Answer:

Dot product = 3×4 + 4×(−3) = 12 − 12 = 0
Angle = 90°

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🔹 PYQ–10 (JEE ADVANCED – FINAL CONCEPT TEST)

Question:
Which of the following quantities remains unchanged during projectile motion (neglect air resistance)?
(a) Speed
(b) Velocity
(c) Horizontal component of velocity
(d) Acceleration

Answer:

Correct option: (c) Horizontal component of velocity

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🎯 WHY THESE QUESTIONS ARE IMPORTANT

• They test understanding, not formulas
• They contain common IIT traps
• They separate top ranks from average students
• Mastering these gives huge confidence

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✅ ADDITIONAL MATERIALS – 7 (IIT PYQs) COMPLETED