Frequency of vibrations means the number of cycles per second.

When a train is rounding a curve, the side thrust on the wheel flanges is prevented by raising the outer edge of the rail.

Efficiency of a screw jack is given by(where α = Helix angle, and φ = Angle of friction.)

If tension in the cable supporting a lift moving downwards is half the tension when it is moving upwards, the acceleration of the lift is

Three forces acting on a rigid body are represented in magnitude, direction and line of action by the three sides of a triangle taken in order. The forces are equivalent to a couple whose moment is equal to