Dynamics Problem (Torque, Acceleration, Velocity - Angular)

An electric motor is running at 1200rpm when its power is cut off for 40 seconds, then turned back on. If the rotor weighs 60lb, has a radius of gyration of 8in, and experiences a power-on net torque of 100lb/in and power-off friction torque of 8lb/in, the rotational speed in rpm of the motor 2 seconds after the power is turned back on is closest to which answer? a. 624 b. 1085 c. 21.5 d. 114 *Please show your work

Dynamics Problem (Tangential Acceleration, Velocity)

A board rides on two driving drums. At the instant shown (*see attached), the board has the acceleration noted. If the board is not slipping on the drums and the total acceleration of the drum contact points is 3m/s[squared], the velocity in m/s of the board at this instant is closest to which answer choice? a. 0.8 b. 0.9 c. 0.6 d. 1.2 *Please see attachment for diagram and figures

Dynamics Problem - Backspin (Friction, Velocity)

A 1.2ft diameter ball is thrown onto a rough surface, such that it has a velocity of 6ft/s and a backspin angular velocity of w. If it is to stop backspinning at the same instant as the velocity is 0, the backspin w in rad/s is what? HINT: The answer is independent of the mass and coefficient of friction. a. 17.8 b. 22.0 c. 25.0 d. 28.1 *Please see attachment for diagram and figures; please show your work.

Dynamics Problem (Torque, Angular Acceleration)

A slender rod of mass Mr has a disk of mass Mo fastened to it at its end. It is pinned at 0 - a "frictionless" pin. The circular frequency in rad/s of the system for small oscillations is what? *Please see attachment for diagram, figures and multiple choice answers; please show your work.

Solve for Force (Engineering Dynamics)

Two forces act on a slender bar that is pinned at (see attachment). The horizontal reaction at 0 is 5 lb to the right, the force F in lb is closes to which answer choise? a) 25 b) 30 c) 15 d) 27 *Please see attachment for equations and diagram