1.The uniform 30 kg bar OB is secured to the accelerating frame in the 30 degree position from the horizontal by the hinge at O and roller at A. if the horizontal acceleration of the frame is a equals 20 m/s^2 compute the force Fa on the roller and the x- and y-components of the force supported by the pin at O.
2.Three point loads 10,000, 7500 and 9000 kN act in line 5m apart near the surface of a soil mass. Calculate the vertical stress at a depth of 4m vertically below the centre (7500kN) load.