Rollercoaster car starts at a height of 90 m at point a and is moving at a speed of 20 m/s on a later hill at point c. assuming friction does not affect the motion of a car, what is its height at point c.

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.