2 A particle is placed on a smooth plane which is inclined at an angle of \(20 ^ { \circ }\) to the horizontal. The particle, of mass 4 kg , is released from rest at a point \(A\) and travels down the plane, passing through a point \(B\). The distance \(A B\) is 5 m .
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1. Find the potential energy lost as the particle moves from point \(A\) to point \(B\).
2. Hence write down the kinetic energy of the particle when it reaches point \(B\).
3. Hence find the speed of the particle when it reaches point \(B\).