A particle ( m=1kg ) slides down a frictionless track (AOC) starting from rest of a point A (height 2 m ). After reaching C, the particle continues to move freely in air as a projectile. When it leading its highest point P (height 1 m ) the kinetic energy of the particle (in J ) is: (Figure drawn is schematic and not to scale (take g=10ms−2 )
Answer: 10
Solution
The track is frictionless, so mechanical energy is conserved from the start to the top of the subsequent flight. Starting from rest at height 2m, the total energy is mghA=1×10×2=20J. At the highest point P, height 1m, the potential energy is mghP=1×10×1=10J; only the horizontal velocity survives there, so the kinetic energy is 20−10=10J.
JEE Main · 2020 · 07 Jan 2020 · Shift 1 · Integer answer
