Verified Solution • 2025–26 Session moderate

QJEEM15Ph640b: JEE Main 2015 Physics - Class 11 JEEM15Ph640b Solution: Two stones are thrown up simultaneously from the edge of a…

Two stones are thrown up simultaneously from the edge of a cliff 240 m high with initial speed of 10 m/s and 40 m/s respectively. Which of the following graph best represents the time variation of relative position of the second stone with respect to the first ?

(Assume stones do not rebound after hitting the ground and neglect air resistance, take g=10m/s2)

(The figures are schematic and not drawn to scale)

Multiple Choice Options

  • A https://ik.imagekit.io/novatra/photos/b957e47eeeb712b1858aabf408eff4a0d2568e0c5acaa144dc7d49081d06e560.webp
  • B https://ik.imagekit.io/novatra/photos/fc2e67c8d1ef9b3424b91bf57b3d6f17a073d98b0a88d16d1e3891fde53dc658.webp
  • C https://ik.imagekit.io/novatra/photos/1386bb8c014bc84bb7dd61bef2734d6995befc79bfbef21ea8a1a7a2db0de451.webp
  • D https://ik.imagekit.io/novatra/photos/e85891492674588e8f9a7cd095a5d38cdc601e85c637793c848bbeefe9793e5e.webp

Step-by-Step Verified Solution

Using h=ut+12gt2

y1=10t−5t2;y2=40t−5t2

∴ y2−y1=30t for t≤8s.

Curve will be straight line when t≤8s.

when stone 1 reaches the ground then y1=−240m,andt=8s

for t>8s.

y2−y1=40t+12gt2−240

So, it will be a parabolic curve till stone 2 reaches the ground. And parabola should opens upward as coefficient of t2 is positive.

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