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A ball of mass 100 g is projected with velocity 20 m/s at 60° with horizontal. The decrease in kinetic energy of the ball during the motion from point of projection to highest point is

Asked in JEE Main 22nd Jan 2nd Shift 2025 · Energy conservation on tracks and inclines

• (1) 15 J
• (2) Zero
• (3) 5 J
• (4) 20 J

Step-by-step solution

Why the other options are wrong

• (2) Comes from confusing kinetic energy with total mechanical energy; the total is conserved, the kinetic part is not.
• (3) Comes from using cos² 60°; 5 J is the kinetic energy remaining at the top, not the decrease.
• (4) Comes from assuming the ball is momentarily at rest at the top; the horizontal component survives.

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