Human reaction time is usually about 0.20 s. If your lab partner holds a ruler between your finger and thumb and releases it without warning,
how far can you expect the ruler to fall before you catch it? (Disregard air
resistance. g = 9.81 m/s2.)

Asolid round steel rod 6.25 mm in diameter and 375 mm long is rigidly bonded to the end of solid square brass rod 25 mm on a side and 300 mm long. the geometric axes of the bare are along the same line. an axial tensile force of 5.4 kn is applied at the extreme ends of the assembly. for steel e = 200 gpa and for brass e = 90 gpa. determine the total elongation for the assembly.