A constant horizontal pull of magnitude 20N is applied to a toy car, but the direction of pull is changed in different trials while the car moves 5m in a straight line.
(i) Calculate the work done when the pull makes an angle of 60∘ with the displacement.
(ii) Without doing any further calculation, state whether the work done will be positive, zero or negative if the pull is applied at 110∘ to the displacement. Justify your answer.
(iii) Determine the value of the angle θ (between 0∘ and 180∘) at which the work done by the same pull over the same displacement will be zero.