Assignment 7 Môn Cơ lý thuyết 1 | Đại học Sư phạm Kỹ thuật Thành phố Hồ Chí Minh

lOMoAR cPSD| 58675420 Assignment 7 MECHANICS II: MECH 220 (due on November 16)
Problems from Hibbeler: 16.112, 16.139, 16.146, 17.36, 17.57, 17.82, 17.94
16.112 – The hoop is cast on the rough surface such that it has an angular velocity = 4 rad/s
and an angular acceleration = 5 rad/s2. Also, its center has a velocity of vO = 5 m/s and a
deceleration aO = 2m/s2. Determine the acceleration of point B at this instant.
16.139 – The man stands on the platform at O and runs out toward the edge such that when he is
at A, y = 5 ft, his mass center has a velocity of 2 ft/s and an acceleration of 3ft/s2, both measured
relative to the platform and directed along the positive y axis. If the platform has the angular
motions shown, determine the velocity and acceleration of his mass center at this instant.
16.146 – The wheel is rotating with the angular velocity and angular acceleration at the instant
shown. Determine the angular velocity and angular acceleration of the rod at this instant. The
rod slides freely through the smooth collar. lOMoAR cPSD| 58675420
17.36 – The forklift travels forward with a constant speed of 9 ft/s. Determine the shortest
stopping distance without causing any of the wheels to leave the ground. The forklift has a
weight of 2000 lb with center of gravity at G1, and the load weights 900 lb with center of gravity
at G2. Neglect the weight of the wheels.
17.57 – Cable is unwound from a spool supported on small rollers at A and B by exerting a force
of T = 300 N on the cable in the direction shown. Compute the time needed to unravel 5 m of
cable from the spool if the spool and cable have a total mass of 600 kg and a centroidal radius of
gyration of kO = 1.2 m. For the calculation, neglect the mass of the cable being unwound and the
mass of the rollers at A and B. The rollers turn with no friction. lOMoAR cPSD| 58675420
17.82 – The 50-kg uniform beam (slender rod) is lying on the floor when the man exerts a force
of F = 300 N on the rope, which passes over a small smooth peg at C. Determine the initial
angular acceleration of the beam. Also find the horizontal and vertical reactions on the beam at
A (considered to be a pin) at this instant.
17.94 – The uniform 50-lb board is suspended from cords at C and D. If these cords are
subjected to constant forces of 30 lb and 45 lb, respectively, determine the initial acceleration of
the board’s center and the board’s angular acceleration. Assume the board is a thin plate.
Neglect the mass of the pulleys at E and F.