Astepped shaft abc consisting of two solid circular segments is subjected to torques t1 = 20,000 lb-in and t2 = 8,000 lb-in acting in opposite directions. the larger diameter of the shaft is d1 = 2.25 in, and the smaller diameter is d2 = 1.75 in. if the radius of curvature at the transition between the larger and smaller diameters is a quarter circle, calculate the maximum shear stress τmax in the shaft.

Acave rescue team lifts an injured spelunker directly upward and out of a sinkhole by means of a motor-driven cable. the lift is performed in three stages, each requiring a vertical distance of 10.0 m: (a) the initially stationary spelunker is accelerated to a speed of 4.90 m/s; (b) he is then lifted at the constant speed of 4.90 m/s; (c) finally he is decelerated to zero speed. how much work is done on the 68.0 kg rescue by the force lifting him during each stage?

Explain why electric current cannot exist if a current doesn't have a voltage source.

The experiment done in lab is repeated, using a ball that has unknown mass m. you plot your data in the form of f 2 versus m/l, with f in rev/s, m in kg, and l in m. your data falls close to a straight line that has slope 3.19 m/(kg · s2). use g = 9.80 m/s2 and calculate the mass m of the ball.