Answer:
Net work done=-332.033 N m
Explanation:
To get the direction in which the door will move, we have to calculate the work done by both the businessman and the boy.
The formula for the work done can be expressed as;
Work done=Force exerted×Perpendicular distance from the point of action to the turning point(hub)
a). Work done by the businessman
Since the businessman pushes to the right of the hub, the revolving door will rotate counter-clockwise. We can assume that all counter-clockwise movements are positive
Work done=Force exerted×Perpendicular distance from the point of action to the turning point(hub)
where;
Force exerted=533 N
Perpendicular distance from the point of action to the turning point(hub)=0.539 m
replacing in the expression above;
Work done=(0.539×533)=287.287 N m
b). Work done by the boy
Since the boy pushes to the left of the hub, the revolving door will rotate clockwise. We can assume that all clockwise movements are negative
Work done=Force exerted×Perpendicular distance from the point of action to the turning point(hub)
where;
Force exerted=-397 N
Perpendicular distance from the point of action to the turning point(hub)=1.56 m
replacing in the expression above;
Work done=(1.56×-397)=-619.32 N m
c). Net work done
Net work done=Work done by the boy+Work done by the businessman
where;
Work done by the boy=-619.32 N m
Work done by the businessman=287.287 N m
replacing;
Net work done=(-619.32+287.287)=-332.033 N m
Since the net work done is negative it means the door will revolve in the clockwise direction by a value of 332.033 N m
