Question

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 reaching 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 ms^–2)___.

Answer 1

Mechanical energy conservation between A & P

mg × 2 = mg × 1 + K₂

K₂ = mg × 1 = 10 J.

Answer 2

KE = PE₁ – PE₂ = mgh₁ – mgh₂

= 1 × 10 × 2 – 1 × 10 × 1 = 10 J