Engineering Mechanics - Force System Resultants

Exercise :: Force System Resultants - General QuestionsForce System Resultants - General Questions
36.

Express the moment of the couple acting on the pipe on Cartesian vector form. What is the magnitude of the couple moment?

A.
M_{c} = (37.5i -25j ) N-m, M_{c} = 45.1 N-mB.
M_{c} = (25i -37.5j ) N-m, M_{c} = 45.1 N-mC.
M_{c} =45.1k N-m, M_{c} = 45.1 N-mD.
M_{c} =-45.1k N-m, M_{c} = 45.1 N-m

Answer: Option A

Explanation:

37.

Determine the direction (0° _{} _{} _{} 180°) of the 30-lb force F so that the moment of F about point A has the maximum magnitude.

A.
_{} = 36.9°B.
_{} = 53.1°C.
_{} = 127.0°D.
_{} = 90.0°

Answer: Option A

Explanation:

38.

Determine the moment of force F_{2} about point A on the beam.

A.
M2 = 800 ft-lb _{} B.
M2 = 50 ft-lb _{} C.
M2 = 600 ft-lb _{} D.
M2 = 37.5 ft-lb _{}

Answer: Option C

Explanation:

39.

The distributed loadings of soil pressure on the sides and bottom of a spread footing are shown. Simplify this system to a single resultant force and couple moment acting at A. What is the resultant force F and the couple moment M?

A.
F = (72i + 125j )N, M = 83.5 N-m CCWB.
F = (144i + 125j )N, M = 135.7 N-m CCWC.
F = (144i + 125j )N, M = 83.5 N-m CCWD.
F = (72i + 125j )N, M = 102.1 N-m CCW

Answer: Option D

Explanation:

40.

Replace the two forces acting on the tree branches by an equivalent force and couple moment acting at point O .

A.
R = (60i +198j -36k ) N, M = (747i +18j -924k ) N-mB.
R = (60i +18j -324k ) N, M = (747i +18j -924k ) N-mC.
R = (60i +198j -36k ) N, M = (360i +1260j -414k ) N-mD.
R = (60i +18j -324k ) N, M = (360i +1260j -414k ) N-m

Answer: Option B

Explanation: