*4–68. the c83400-red-brass rod ab and 2014-t6- aluminum rod bc are joined at the collar b and fixed connected at their ends. if there is no load in the members when t1 = 50°f, determine the average normal stress in each member when t2 = 120°f. also, how far will the collar be displaced? the cross-sectional area of each member is 1.75 in2.

An object is located 30.0 cm from a concave mirror. the focal length is 15.0 c,. what is the image distance? a. 30.0 cm b. -10 cm c. 10.0 cm d. -30.0 cm

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 11.0 m: (a) the initially stationary spelunker is accelerated to a speed of 4.80 m/s; (b) he is then lifted at the constant speed of 4.80 m/s; (c) finally he is decelerated to zero speed. how much work is done on the 78.0 kg rescue by the force lifting him during each stage

Astone is thrown into a pond. what happens to the amplitude of the resulting waves as they get farther from the point where the stone hit the water? explain.