Q 11-05-164JEE MainJEE Main 2020 (7 Jan, Shift 1)Easy
A particle ($m = 1$ kg) slides down a frictionless track (AOC) starting from rest at a point A (height $2$ m). After reaching C, the particle continues to move freely in air as a projectile. When it reaches 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 $g = 10\ \text{m s}^{-2}$)
Numerical value type. Enter your answer.
Answer: 10
There is no friction or air resistance, so mechanical energy is conserved from A to P:
$$mgh_A = mgh_P + K_P \Rightarrow K_P = 1\times10\times(2 - 1) = 10\ \text{J}$$
Solution by Sreeraj P, M.Sc Physics