A wheel with a radius of 45.0 $\mathrm{cm}$ rolls without slipping along a horizontal floor (Fig. $3-37 ) .$ At time $t_{1}$ the dot $P$ painted on the rim of the wheel is at the point of contact between the wheel and the floor. At a later time $t_{2},$ the wheel has rolled through one-half of a revolution.
What are (a) the magnitude and (b) the angle (relative to the floor) of the displacement of $P ?$