A ball is thrown vertically up (taken as +z -axis) from the ground. The correct momentumheight ( p−h ) diagram is:
(A)(see structure)
(B)(see structure)✓ Correct
(C)(see structure)
(D)(see structure)
Answer: (B)
Solution
Throwing the ball up, energy conservation gives v2=u2−2gh, and writing v=p/m this becomes h=2gu2−2gm2p2. So h is a downward-opening parabola in p: the height is greatest where p=0 (the top of the flight) and falls to zero where ∣p∣ is largest (at launch and at landing), and it is symmetric in the sign of p. The curve carrying this parabolic, symmetric shape is the correct momentum-height graph.
JEE Main · 2019 · 09 Apr 2019 · Shift 1 · Single correct option