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1. Opposing shearing forces of 3000 N are applied to the 4.00-cm × 5.00-cm faces

ID: 1487032 • Letter: 1

Question

1. Opposing shearing forces of 3000 N are applied to the 4.00-cm × 5.00-cm faces of a metal block measuring 3.00 cm × 4.00 cm × 5.00 cm. By what amount does the block become slanted? The shear modulus for this metal is 8.10 × 1010 N/m2.

2. On a cold winter day, the outside temperature is -20°C and the inside temperature is maintained at 20°C. There is a net heat flow to the outside through the walls, roof, etc., of 25 kW. What is the rate of increase of the entropy of the universe as a result of this heat flow?

A. 1.54 × 10-6 m B. 9.88 × 10-7 m C. 5.56 × 10-7 m D. 6.98 × 10-6 m E. 3.08 × 10-6 m

Explanation / Answer

since shear modulus is,

G =Fl/Ax

here,F = 3000 N

G = 8.10 x 10^10 N/m^2

l = 3 cm = 0.03 m

A = (0.04)(0.05) = 20*10^-4 m^2

and x is transverse displacement

thus x = Fl/AG

= (3000 N)(0.03 m)/(20*10^-4 m^2)(8.10 x 10^10 N/m^2)

=5.56*10^-7 m

therefore, trhe correct option is C