ENGR 215 ~ Dynamics Section 18

Lecture Example 1: At the instant shown, link AB has angular velocity ωAB = 2 rad/sec. If each link is considered as a uniform slender bar with weight density of 0.5 lb/in, determine the total kinetic energy of the system.

Lecture Example 2: A yo-yo has weight of 0.3 lb and radius of gyration kO=0.06 ft. If it is released from rest, determine how far it must descend in order to attain angular velocity ω = 70 rad/sec. Neglect the mass of the string and assume that the string is wound around the central peg such that the mean radius at which it unravels is r = 0.02 ft.

Lecture Example 3: A ball of mass m and radius r is cast onto the horizontal surface such that it rolls without slipping. Determine the minimum speed vG of its mass center G so that it rolls completely around the loop of radius R + r without leaving the track.

Lecture Example 4: The compound disk pulley consists of a hub and attached outer rim. If it has mass, mdisk=3kg and radius of gyration kG=45mm determine the speed of block A after A descends distance 0.2m from rest. Blocks A and B each have a mass mb=2kg. Neglect the mass of the cords.

Lecture Example 5: The assembly consists of two 3 ft. bars of weight 8 lb. which are pin connected to the two disks with a radius of 0.5 ft. and a weight of 10 lb. If the bars are released from rest at = 60, determine their angular velocities at the instant = 0. Assume the disks roll without slipping.