The uniform cantilever carries a uniformly distributed load w and is supported on a rigid knife edge at the end D.
Suppose P is the force on the support at D.
Then we regard Figure(i) as the superposition of the effects of P and w acting separately.
If w acts alone, the deflection at D is given by equation, and has the value
If the reaction P acted alone, there would be an upward deflection
at D. If the support maintains zero deflection at D,