Q3:A tow truck pulls a car that is stuck in the mud, with a force of 2 500 N as shown. The tow cable is
under tension and therefore pulls downward and to the left on the pin at its upper end. The light pin is
held in equilibrium by forces exerted by the two bars A and B. Each bar is a strut: that is, each is a bar
whose weight is small com-pared to the forces it exerts, and which exerts forces only through hinge pins at its ends.
Each strut exerts a force directed parallel to its length.
(i) Determine the force of tension or compression in each strut. Proceed as follows: Make a guess as to which way
(pushing or pulling) each force acts on the top pin. (4)
(ii) Draw a free-body diagram of the pin. Use the condition for equilibrium of the pin to translate the free-body
diagram into equations. From the equations calculate the forces exerted by struts A and B. 4A negative answer
means the direction should be reversed, but the absolute value correctly gives the magnitude of the force. (8)
(iii)If a strut pulls on a pin, it is in tension. If it pushes, the strut is in compression. Identify whether each strut is in
tension or in compression
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