Aladder of mad and length l is released from rest at (theta) = 90 degrees. if the friction at o between the ladder and ground is sufficient to prevent slipping, determine the normal and frictional forces at o as a function of the angle theta if the ladder is given a slight nudge from rest at theta = 90. model the ladder as a uniform slender bar.

What precautions should you take to prevent injuries when dealing with heavy loads?

Aloaded platform of total mass 500 kg is supported by a dashpot and by a set of springs of effective stiffness 72 kn/m. it is observed that when the platform is depressed through a distance x = 12.5 cm below its equilibrium position and then released without any initial velocity; it reaches its equilibrium position in the shortest possible time without overshoot. find the position and velocity of the loaded platform 0.10 sec. after its release. if a further load of 400 kg is added to the platform, find, i) the frequency of damped vibrations, and i) the amplitude of vibration after 2 complete oscillations, given that the initial amplitude is 15 cm.

Modern high speed trains do not have perpendicular expansion gaps where rails are joined end-to-end any more they are mostly welded together but what might happen if there was a spell of particularly hot weather that causes inspection of the tracks?