ω rad/sec is the angular velocity of a crank whose radius is r. If it makes θ° with inner dead centre and obliquity of the connecting rod l is φ, the velocity v of the piston, is given by the equation

• ω2(l cos φ + r sin φ tan θ)
• ω2(l sin φ + r cos φ tan θ)
• ω(l sin φ + r cos φ tan θ)
• ω2(l sin φ - r cos θ tan φ).