# The Motion

**Classical Mechanics**Level 3

An object A is kept fixed at the point \( x=3 \text { m} \) and \(y=1.25 \text{ m} \) on a plank P raised above the ground. At time \(t=0\) it starts moving along \(+x\) direction with an acceleration of \(1.5 ms^{-2}\). At that instant a stone is projected with a speed of \(\vec{u} \) a stationary person on ground observes the stone hits the object work an angle of 45 degree during downward motion. Find \(\vec{u} \) and time taken to hit. Take \( g = 10 \text{ m/s}^2 \).