Physics 211 Spring 2009 Syracuse University Homework Problem Set 13 p.1
Physics 211 Problem Set 13 Due Fri, 04/24/09
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1. Old MacDonald had a farm, and on that farm he had a gate (see below). The gate is 3m
wide and 1.8m high, with hinges attached to the top and bottom. The guy wire makes
an angle of 300 with the top of the gate and is tightened by a turn buckle to a tension of
200 N. The mass of the gate is 40kg.
(a) Determine the horizontal force exerted on the gate by the bottom hinge.
(b) Find the horizontal force exerted on the gate by the upper hinge.
(c) Determine the combined vertical force exerted by both hinges.
Hints: You should start by drawing extended free-body diagram for the gate. Label
the forces clearly. Write down three equilibrium conditions for the gate before
you try to answer any questions.
Reaction forces from the hinges may have both horizontal and vertical
components. Calculate torque relatively to the upper hinge as one of your
equilibrium conditions (this simplifies algebra to be done).
