BEDFORD ESTATICA

Problem 2.1 In Active Example 2.1, suppose that the

vectors U and V are reoriented as shown. The vector

V is vertical. The magnitudes are jUj D 8 and jVj D 3.

Graphically determine the magnitude of the vector

U C 2V.

U V

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Solution: Draw the vectors accurately and measure the resultant.

R D jU C 2Vj D 5.7 R D 5.7

Problem 2.2 Suppose that the pylon in Example 2.2 is

moved closer to the stadium so that the angle between

the forces FAB and FAC is 50°. Draw a sketch of the

new situation. The magnitudes of the forces are jFABj D 100 kN and jFACj D 60 kN. Graphically determine the

magnitude and direction of the sum of the forces exerted

on the pylon by the cables.

Solution: Accurately draw the vectors and measure the magnitude

and direction of the resultant

jFAB C FACj D 146 kN

˛ D 32°

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Problem 2.3 The magnitude jFAj D 80 lb and the

angle ˛ D 65°. The magnitude jFA C FBj D 120 lb.

Graphically determine the magnitude of FB.

FB

FA

a

FC

Solution: Accurately draw the vectors and measure the magnitude

of FB.

jFBj D 62 lb

Problem 2.4 The magnitudes jFAj D 40 N, jFBj D 50 N, and jFCj D 40 N. The angle ˛ D 50° and ˇ D 80°.

Graphically determine the magnitude of FA C FB C FC.

FB

FA

a

FC

Solution:

...