Question

Chapter 12 Discussion

Instructions: Please complete the four (4) questions below. Once you complete the four questions, please provide your remarks why you believe

your answer is correct in the discussion board.

Consider the object subject to the two forces in Figure. Choose the correct statement with regard to this situation.

The object is in force equilibrium but not torque equilibrium.

The object is in torque equilibrium but not force equilibrium.

The object is in both force equilibrium and torque equilibrium.

The object is in neither force equilibrium nor torque equilibrium.

B. Consider the object subject to the three forces in Figure. Choose the correct statement with regard to this situation.

The object is in force equilibrium but not torque equilibrium.

The object is in torque equilibrium but not force equilibrium.

The object is in both force equilibrium and torque equilibrium.

The object is in neither force equilibrium nor torque equilibrium.

A meterstick is hung from a string tied at the 25-cm mark. A 0.50-kg object is hung from the zero end of the meterstick, and the meterstick is balanced horizontally. What is the mass of the meterstick?

0.25 kg

0.50 kg

0.75 kg

1.0 kg

2.0 kg

impossible to determine

Choose the correct answer for the elastic modulus that describes the relationship between stress and strain for the following system in italics: A block of iron is sliding across a horizontal floor. The friction force between the block and the floor causes the block to deform.

Young

Answer 1

a)
The object is in force equilibrium but not torque equilibrium.

this is because both forces are equal but in opposite direction, but they create torque with the center of mass in the same rotational direction.
b)

The object is in torque equilibrium but not force equilibrium.

this is because the 3 forces pass across the center of mass, so they do not create torque, but the sum of these ones is different to zero.

$g*0.5*0.25+0.25*m*g*0.125=0.75*m*g*0.375$
$0.5*0.25+0.25*m*0.125=0.75*m*0.375$
$0.125+0.03125*m=0.28125*m$
$0.125=0.28125*m-0.03125*m$
$0.125/0.25=m$
$m=0.5g$

d)
shear modulus

I took the images from Serway Chapter 20, 6 edition