5. Exercises
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| + | ===Exercise 5.3=== | ||
| + | <div class="ovning"> | ||
| + | Four cables are attached to the top of a telegraph pole. The tensions in these cables are shown in the diagram below. The forces acting on the pole are in equilibrium. | ||
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| + | [[Image:E5.3.GIF]] | ||
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| + | Assume that all the forces act in a horizontal plane. | ||
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| + | (a) Express the force with magnitude ''Q'' in terms of the unit vectors <math>\mathbf{i}</math> | ||
| + | and <math>\mathbf{j}</math>. | ||
| + | (b) Find ''Q'' and the angle <math>\alpha </math>. | ||
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| + | </div>{{#NAVCONTENT:Answer|Answer 5.3|Solution a|Solution 5.3a|Solution b|Solution 5.3b}} | ||
Revision as of 11:10, 10 September 2009
| Theory | Exercises |
Exercise 5.1
1. A particle of mass 20 kg is at rest on a rough slope inclined at 20\displaystyle {}^\circ to the horizontal.
a) Draw a diagram to show the forces acting on the particle.
b) Find the magnitude of the normal reaction force acting on the particle.
c) Find the magnitude of the friction force acting on the particle.
d) Find an inequality that \displaystyle \mu , the coefficient of friction between the particle and the plane, must satisfy.
Loading...Exercise 5.2
An object, of mass 50 kg, is supported by two ropes, as shown in the diagram below. The diagram also shows how gravity acts on the object.
a) Find \displaystyle {{T}_{1}}.
b) Find \displaystyle {{T}_{2}}.
Exercise 5.3
Four cables are attached to the top of a telegraph pole. The tensions in these cables are shown in the diagram below. The forces acting on the pole are in equilibrium.
Assume that all the forces act in a horizontal plane.
(a) Express the force with magnitude Q in terms of the unit vectors \displaystyle \mathbf{i} and \displaystyle \mathbf{j}. (b) Find Q and the angle \displaystyle \alpha .
