Jimmy walks at 60 meters per minute. It takes him 21 minutes to walk from home to school. If he runs at 180 meters per minute, how long does it take him to run from school to home

Determine the largest intensity w of the uniform loading that can be applied to the frame without causing either the average normal stress or the average shear stress at section b–b to exceed σ=19 mpa and τ=24 mpa, respectively.