Question 1

For a body to be equilibrium under the combined action of several forces:

Accepted Answer

A)  all the forces must be applied at the same point 
B)  all of the forces are composed of pairs of equal and opposite forces 
C)  any two of these forces must be balanced by a third force 
D)  the sum of the torques about any point must equal zero 
E)  the lines of action of all the forces must pass through the center of gravity of the body 
A)  all the forces must be applied at the same point 
B)  all of the forces are composed of pairs of equal and opposite forces 
C)  any two of these forces must be balanced by a third force 
D)  the sum of the torques about any point must equal zero 
E)  the lines of action of all the forces must pass through the center of gravity of the body

Question 2

A 4.0 m steel beam with a cross sectional area of 1.0 * 10-2 m2 and a Young's modulus of 2.0 *1011 N/m2 is wedged horizontally between two vertical walls. In order to wedge the beam, it is compressed by 0.020 mm. If the coefficient of static friction between the beam and the walls is 0.70, the maximum mass (including its own) it can bear without slipping is:

Accepted Answer

A)  0 
B)  3.6 kg 
C)  36 kg 
D)  71 kg 
E)  710 kg 
A)  0 
B)  3.6 kg 
C)  36 kg 
D)  71 kg 
E)  710 kg

Question 3

A picture is to be hung from the ceiling by means of two wires. Order the following arrangements of the wires according to the tension in wire B, from least to greatest.

Accepted Answer

A)  I, II, III 
B)  III, II, I 
C)  I and II tie, then III 
D)  II, I, III 
E)  all tie 
A)  I, II, III 
B)  III, II, I 
C)  I and II tie, then III 
D)  II, I, III 
E)  all tie

Question 4

Young's modulus can be correctly given in:

Accepted Answer

A)  N.m 
B)  N.m2 
C)  N.m/s 
D)  N/m 
E)  joules 
A)  N.m 
B)  N.m2 
C)  N.m/s 
D)  N/m 
E)  joules

Question 5

Three identical uniform rods are each acted on by two or more forces, all perpendicular to the rods. Which of the rods could be in static equilibrium if an additional force is applied at the center of mass of the rod?

Accepted Answer

A)  Only 1 
B)  Only 2 
C)  Only 3 
D)  Only 1 and 2 
E)  All three 
A)  Only 1 
B)  Only 2 
C)  Only 3 
D)  Only 1 and 2 
E)  All three

Question 6

A horizontal beam of weight W is supported by a hinge and cable as shown. The force exerted on the beam by the hinge has a vertical component that must be:

Accepted Answer

A)  nonzero and up 
B)  nonzero and down 
C)  nonzero but not enough information given to know whether up or down 
D)  zero 
E)  equal to W 
A)  nonzero and up 
B)  nonzero and down 
C)  nonzero but not enough information given to know whether up or down 
D)  zero 
E)  equal to W

Question 7

A 960-N block is suspended as shown. The beam AB is weightless and is hinged to the wall at A. The tension force of the cable BC has magnitude:

Accepted Answer

A)  720 N 
B)  1200 N 
C)  1280 N 
D)  1600 N 
E)  none of these 
A)  720 N 
B)  1200 N 
C)  1280 N 
D)  1600 N 
E)  none of these

Question 8

The ultimate strength of a sample is the stress at which the sample:

Accepted Answer

A)  returns to its original shape when the stress is removed 
B)  remains underwater 
C)  breaks 
D)  bends 180$\degree$ 
E)  does none of these 
A)  returns to its original shape when the stress is removed 
B)  remains underwater 
C)  breaks 
D)  bends 180$\degree$ 
E)  does none of these

Question 9

A meter stick on a horizontal frictionless table top is pivoted at the 80-cm mark. A force   is applied perpendicularly to the end of the stick at 0 cm, as shown. A second force   (not shown) is applied perpendicularly at the 60-cm mark. The forces are horizontal. If the stick does not move, the force exerted by the pivot on the stick:

Accepted Answer

A)  must be zero 
B)  must be in the same direction as   and have magnitude   
C)  must be directed opposite to   and have magnitude   
D)  must be in the same direction as   and have magnitude   
E)  must be directed opposite to   and have magnitude   
A)  must be zero 
B)  must be in the same direction as   and have magnitude   
C)  must be directed opposite to   and have magnitude   
D)  must be in the same direction as   and have magnitude   
E)  must be directed opposite to   and have magnitude

Question 10

The location of which of the following points within an object might depend on the orientation of the object?

Accepted Answer

A)  Its center of mass 
B)  Its center of gravity 
C)  Its geometrical center 
D)  Its center of momentum 
E)  None of the above 
A)  Its center of mass 
B)  Its center of gravity 
C)  Its geometrical center 
D)  Its center of momentum 
E)  None of the above

Question 11

The pull P is just sufficient to keep the 14-N block and the weightless pulleys in equilibrium as shown. The tension T in the upper cable is:

Accepted Answer

A)  14 N 
B)  28 N 
C)  16 N 
D)  9.33 N 
E)  18.7 N 
A)  14 N 
B)  28 N 
C)  16 N 
D)  9.33 N 
E)  18.7 N

Question 12

The diagram shows a stationary 5-kg uniform rod (AC), 1 m long, held against a wall by a rope (AE) and friction between the rod and the wall. To use a single equation to find the force exerted on the rod by the rope at which point should you place the reference point for computing torque?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  D 
E)  E 
A)  A 
B)  B 
C)  C 
D)  D 
E)  E

Question 13

A shearing force of 50 N is applied to an aluminum rod with a length of 10 m, a cross-sectional area of 1.0 *10-5 m, and shear modulus of 2.5 *1010N/m2. As a result the rod is sheared through a distance of:

Accepted Answer

A)  zero 
B)  1.9 mm 
C)  1.9 cm 
D)  19 cm 
E)  1.9 m 
A)  zero 
B)  1.9 mm 
C)  1.9 cm 
D)  19 cm 
E)  1.9 m

Exam 12: Equilibrium and Elasticity

For a body to be equilibrium under the combined action of several forces:

A picture is to be hung from the ceiling by means of two wires. Order the following arrangements of the wires according to the tension in wire B, from least to greatest.

Young's modulus can be correctly given in:

Three identical uniform rods are each acted on by two or more forces, all perpendicular to the rods. Which of the rods could be in static equilibrium if an additional force is applied at the center of mass of the rod?

A horizontal beam of weight W is supported by a hinge and cable as shown. The force exerted on the beam by the hinge has a vertical component that must be:

A 960-N block is suspended as shown. The beam AB is weightless and is hinged to the wall at A. The tension force of the cable BC has magnitude:

The ultimate strength of a sample is the stress at which the sample:

The location of which of the following points within an object might depend on the orientation of the object?

The pull P is just sufficient to keep the 14-N block and the weightless pulleys in equilibrium as shown. The tension T in the upper cable is:

The diagram shows a stationary 5-kg uniform rod (AC), 1 m long, held against a wall by a rope (AE) and friction between the rod and the wall. To use a single equation to find the force exerted on the rod by the rope at which point should you place the reference point for computing torque?

A shearing force of 50 N is applied to an aluminum rod with a length of 10 m, a cross-sectional area of 1.0 *10-5 m, and shear modulus of 2.5 *1010N/m2. As a result the rod is sheared through a distance of:

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A shearing force of 50 N is applied to an aluminum rod with a length of 10 m, a cross-sectional area of 1.0 10-⁵ m, and shear modulus of 2.5 10¹⁰N/m^2.As a result the rod is sheared through a distance of: