Chapter 11, Problem 70GP

A projectile with mass m is launched from the ground and follows a trajectory given by

$\stackrel{\to }{r}=\left({\upsilon }_{x0}t\right)\hat{i}+\left({\upsilon }_{y0}t-\frac{1}{2}g{t}^2\right)\hat{j}$

where υ_x0 and υ_y0 are the initial velocities in the x and y direction, respectively, and g is the acceleration due to gravity. The launch position is defined to be the origin. Determine the torque acting on the projectile about the origin using (a) $\stackrel{\to }{\tau }=\stackrel{\to }{r}\times \stackrel{\to }{F}$, (b) $\stackrel{\to }{\tau }=d\stackrel{\to }{\text{L}}\text{/}dt$.