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1. For a system in static equilibrium, which statement below best describes the

ID: 1776274 • Letter: 1

Question

1. For a system in static equilibrium, which statement below best describes the physics of the system?

A. Sum of forces in the x-direction=0

B. Sum of forces in the y-direction=0

C. Sum of torques around an axis=0

D. All the above

2. You are designing a mechanical arm to be used on an assembly line. You decide to use a beam L in length with a mass of M. The beam will be pivoted at one end, and a cable attached to a motor—acting like a bicep— will raise and lower the arm in a manner similar to how a human arm works. The cable attaches a distance d from the pivot point. When the beam is horizontal, the cable makes and angle of theta with the beam. The center of mass of the beam is a distance r from the pivot point. You wish to find the force F the cable must exert to hold the arm in the horizontal position. The acceleration of gravity is g. Which formula is correct?

A.      Mgd

F=        ------------------

              r sin(theta)

B.        Mgr

F=     ------------------

            d sin(theta)

C. MgL

F=             ------------------

                    r sin(theta)

3.

Suppose

L=1.2 m

M=0.3 kg

d=0.1 m

theta=82 degrees

r=0.6 m.

What is the value of F?

A. 18    B. 28     C.38

4. For the experiment, to what force range should the force probe be set?

A. 0-10

B 0-50

Explanation / Answer

1. For a system in static equilibrium, which statement below best describes the physics of the system?

A. Sum of forces in the x-direction=0

B. Sum of forces in the y-direction=0

C. Sum of torques around an axis=0

D. All the above

Since in equilibrium , net torque and net force must be 0.