In the figure shown, a particle is released from the position A on ...

In the figure shown, a particle is released from the position A on a smooth track. When the particle reaches
P at \( \mathrm{B} \), then normal reaction on it by the track is

W
(1) \( m g \)
(2) \( 2 m g \)
(3) \( \frac{2}{3} m g \)
(4) \( \frac{m^{2} g}{h} \)