Find the velocity of the piston and the angular velocity of AB about point A. The crank O-A rotates at 200 rev/min clockwise. Note that the vector ob is at 45° to the horizontal as the piston must slide in this direction. The values given are: 200 rev/min, 140 mm, 40 mm, 45°, 30°. Figure 17. Answer: 0.49 m/s and 6.92 rad/s.