Arock is dropped from rest from a height h above the ground. it falls and hits the ground with a
speed of 11 m/s. from what height should the rock be dropped so that its speed on hitting the ground
is 22 m/s? neglect air resistance

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.