Using a forked rod, a 0.7-kg smooth peg P is forced to move along the vertical slotted path r = (0.5 ) m, where

Using a forked rod, a 0.7-kg smooth peg P is forced to move along the vertical slotted path r = (0.5 θ) m, where θ is in radians. The angular position of the arm is θ = (π8t2) rad where t is in seconds. The peg is in contact with only one edge of the rod and slot at any instant. 

P r = (0.50) m