(Multiple choice) (1) True and False (a) F = 0 is sufficient for static equilibrium to exist....

(Multiple choice)

(1) True and False

(a) ΣF = 0 is sufficient for static equilibrium to exist. 

(b) ΣF = 0 is necessary for static equilibrium to exist. 

(c) In static equilibrium, the net torque about any point is zero. 

(d) An object is in equilibrium only when there are no forces acting on it.

(2) True and False

The center of gravity is always at the geometric center of a body.

(3)

Must there be any material at the center of gravity of an object?

(4)

An aluminum wire and a steel wire of the same length L and diameter d are joined to form a wire of length 2L. The wire is fastened to the roof and a weight W is attached to the other end. Neglecting the mass of the wires, which of the following statements is true? 

(a) The aluminum portion will stretch by the same amount as the steel portion. 

(b) The tensions in the aluminum portion and the steel portion are the same. 

(c) The tension in the aluminum portion is greater than that in the steel portion. 

(d) None of the above statements is true.

(5)

The horizontal bar in Figure will remain horizontal if 

(a) L₁ = L₂ and R₁ = R₂. 

(b) L₁ = L₂ and M₁ = M₂. 

(c) R₁ = R₂ and M₁ = M₂. 

(d) L₁M₁ = L₂M₂. 

(e) R₁L₁ = R₂L₂.

(6)

Which of the following could not have units of N/m²? 

(a) Young's modulus 

(c) Stress 

(b) Shear modulus 

(d) Strain

Transcribed Image Text:

R2 R1 L2 M1 M2