Question 1

The conditions that the sum of forces and the sum of the torques both vanish:

Accepted Answer

A)  hold for every solid body in equilibrium 
B)  hold only for elastic solid bodies in equilibrium 
C)  hold for every solid body 
D)  are always sufficient to calculate the forces on a solid object in equilibrium 
E)  are sufficient to calculate the forces on a solid object in equilibrium only if the object is elastic 
A)  hold for every solid body in equilibrium 
B)  hold only for elastic solid bodies in equilibrium 
C)  hold for every solid body 
D)  are always sufficient to calculate the forces on a solid object in equilibrium 
E)  are sufficient to calculate the forces on a solid object in equilibrium only if the object is elastic

Question 2

A cube with edges exactly 2 cm long is made of material with a bulk modulus of 3.5 * 109 N/m2. When it is subjected to a pressure of 3.0 *105 Pa its volume is:

Accepted Answer

A)  7.31 cm3 
B)  7.99931 cm3 
C)  8.00069 cm3 
D)  8.69 cm3 
E)  none of these 
A)  7.31 cm3 
B)  7.99931 cm3 
C)  8.00069 cm3 
D)  8.69 cm3 
E)  none of these

Question 3

A window washer attempts to lean a ladder against a frictionless wall. He finds that the ladder slips on the ground when it is placed at an angle of less than 75$\degree$ to the ground but remains in place when the angle is greater than 75$\degree$. The coefficient of static friction between the ladder and the ground:

Accepted Answer

A)  is about 0.13 
B)  is about 0.27 
C)  is about 1.3 
D)  depends on the mass of the ladder 
E)  depends on the length of the ladder 
A)  is about 0.13 
B)  is about 0.27 
C)  is about 1.3 
D)  depends on the mass of the ladder 
E)  depends on the length of the ladder

Question 4

A uniform ladder is 10 cm long and weighs 400 N. It rests with its upper end against a frictionless vertical wall. Its lower end rests on the ground and is prevented from slipping by a peg driven into the ground. The ladder makes a 30$\degree$ angle with the horizontal. The force exerted on the wall by the ladder is:

Accepted Answer

A)  48 N 
B)  74 N 
C)  120 N 
D)  350 N 
E)  610 N 
A)  48 N 
B)  74 N 
C)  120 N 
D)  350 N 
E)  610 N

Question 5

To shear a cube-shaped object, forces of equal magnitude and opposite directions might be applied:

Accepted Answer

A)  to opposite faces, perpendicular to the faces 
B)  to opposite faces, parallel to the faces 
C)  to adjacent faces, perpendicular to the faces 
D)  to adjacent faces, neither parallel or perpendicular to the faces 
E)  to a single face, in any direction 
A)  to opposite faces, perpendicular to the faces 
B)  to opposite faces, parallel to the faces 
C)  to adjacent faces, perpendicular to the faces 
D)  to adjacent faces, neither parallel or perpendicular to the faces 
E)  to a single face, in any direction

Question 6

A certain wire stretches 0.90 cm when outward forces with magnitude F are applied to each end. The same forces are applied to a wire of the same material but with three times the diameter and three times the length. The second wire stretches:

Accepted Answer

A)  0.10 cm 
B)  0.30 cm 
C)  0.90 cm 
D)  2.7 cm 
E)  8.1 cm 
A)  0.10 cm 
B)  0.30 cm 
C)  0.90 cm 
D)  2.7 cm 
E)  8.1 cm

Question 7

A 400-N uniform vertical boom is attached to the ceiling by a hinge, as shown. An 800-N weight W and a horizontal guy wire are attached to the lower end of the boom as indicated. The pulley is massless and frictionless. The tension force T of the horizontal guy wire has magnitude:

Accepted Answer

A)  340 N 
B)  400 N 
C)  690 N 
D)  800 N 
E)  1200 N 
A)  340 N 
B)  400 N 
C)  690 N 
D)  800 N 
E)  1200 N

Question 8

A uniform plank XY is supported by two equal 120-N forces at X and Y, as shown. The support at X is then moved to Z (half-way to the plank center). The supporting forces at Y and Z are then:

Accepted Answer

A)  FY = 240 N, FZ = 120 N 
B)  FY = 200 N, FZ = 40 N 
C)  FY = 40 N, FZ = 200 N 
D)  FY = 80 N, FZ = 160 N 
E)  FY = 160 N, FZ = 80 N 
A)  FY = 240 N, FZ = 120 N 
B)  FY = 200 N, FZ = 40 N 
C)  FY = 40 N, FZ = 200 N 
D)  FY = 80 N, FZ = 160 N 
E)  FY = 160 N, FZ = 80 N

Question 9

The 600-N ball shown is suspended on a string AB and rests against the frictionless vertical wall. The string makes an angle of 30$\degree$with the wall. The ball presses against the wall with a force of magnitude:

Accepted Answer

A)  120 N 
B)  300 N 
C)  350 N 
D)  600 N 
E)  690 N 
A)  120 N 
B)  300 N 
C)  350 N 
D)  600 N 
E)  690 N

Question 10

A net torque applied to a rigid object always tends to produce:

Accepted Answer

A)  linear acceleration 
B)  rotational equilibrium 
C)  angular acceleration 
D)  rotational inertia 
E)  none of these 
A)  linear acceleration 
B)  rotational equilibrium 
C)  angular acceleration 
D)  rotational inertia 
E)  none of these

Question 11

The bulk modulus is a proportionality constant that relates the pressure acting on an object to:

Accepted Answer

A)  the shear 
B)  the fractional change in volume 
C)  the fractional change in length 
D)  Young's modulus 
E)  the spring constant 
A)  the shear 
B)  the fractional change in volume 
C)  the fractional change in length 
D)  Young's modulus 
E)  the spring constant

Question 12

A 240-N weight is hung from two ropes as shown. The tension in the horizontal rope has magnitude:

Accepted Answer

A)  0 
B)  656 N 
C)  480 N 
D)  416 N 
E)  176 N 
A)  0 
B)  656 N 
C)  480 N 
D)  416 N 
E)  176 N

Question 13

A uniform 240-g meter stick can be balanced by a 240-g weight placed at the 100-cm mark if the fulcrum is placed at the point marked:

Accepted Answer

A)  75 cm 
B)  60 cm 
C)  50 cm 
D)  40 cm 
E)  80 cm 
A)  75 cm 
B)  60 cm 
C)  50 cm 
D)  40 cm 
E)  80 cm

Question 14

An 80-N uniform plank leans against a frictionless wall as shown. The torque (about point P) applied to the plank by the wall is:

Accepted Answer

A)  40 N.m 
B)  60 N.m 
C)  120 N.m 
D)  160 N.m 
E)  240 N.m 
A)  40 N.m 
B)  60 N.m 
C)  120 N.m 
D)  160 N.m 
E)  240 N.m

Question 15

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)  the sum of the components of all the forces in any direction must equal zero 
D)  any two of these forces must be balanced by a third force 
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)  the sum of the components of all the forces in any direction must equal zero 
D)  any two of these forces must be balanced by a third force 
E)  the lines of action of all the forces must pass through the center of gravity of the body

Question 16

An 800-N man stands halfway up a 5.0 m ladder of negligible weight. The base of the ladder is 3.0 m from the wall as shown. Assuming that the wall-ladder contact is frictionless, the wall pushes against the ladder with a force of:

Accepted Answer

A)  150 N 
B)  300 N 
C)  400 N 
D)  600 N 
E)  800 N 
A)  150 N 
B)  300 N 
C)  400 N 
D)  600 N 
E)  800 N

Question 17

A 160-N child sits on a light swing and is pulled back and held with a horizontal force of 100 N. The magnitude of the tension force of each of the two supporting ropes is:

Accepted Answer

A)  60 N 
B)  94 N 
C)  120 N 
D)  190 N 
E)  260 N 
A)  60 N 
B)  94 N 
C)  120 N 
D)  190 N 
E)  260 N

Question 18

A cube with 2.0-cm sides is made of material with a bulk modulus of 4.7 *105 N/m2. When it is subjected to a pressure of 2.0 * 105 Pa the length in cm of its any of its any of its sides is:

Accepted Answer

A)  0.85 cm 
B)  1.15 cm 
C)  1.66 cm 
D)  2.0 cm 
E)  none of these 
A)  0.85 cm 
B)  1.15 cm 
C)  1.66 cm 
D)  2.0 cm 
E)  none of these

Question 19

Stress can be measured in:

Accepted Answer

A)  N/m2 
B)  N.m2 
C)  N/m 
D)  N.m 
E)  none of these (it is unitless) 
A)  N/m2 
B)  N.m2 
C)  N/m 
D)  N.m 
E)  none of these (it is unitless)

Question 20

A picture P of weight W is hung by two strings as shown. The magnitude of the tension force of each string is T. The total upward pull of the strings on the picture is:

Accepted Answer

A)  2W cos $\theta$ 
B)  T sin $\theta$ 
C)  T cos $\theta$ 
D)  2T sin$\theta$ 
E)  2T cos $\theta$ 
A)  2W cos $\theta$ 
B)  T sin $\theta$ 
C)  T cos $\theta$ 
D)  2T sin$\theta$ 
E)  2T cos $\theta$

Exam 12: Equilibrium and Elasticity

The conditions that the sum of forces and the sum of the torques both vanish:

A cube with edges exactly 2 cm long is made of material with a bulk modulus of 3.5 * 109 N/m2. When it is subjected to a pressure of 3.0 *105 Pa its volume is:

To shear a cube-shaped object, forces of equal magnitude and opposite directions might be applied:

A certain wire stretches 0.90 cm when outward forces with magnitude F are applied to each end. The same forces are applied to a wire of the same material but with three times the diameter and three times the length. The second wire stretches:

A 400-N uniform vertical boom is attached to the ceiling by a hinge, as shown. An 800-N weight W and a horizontal guy wire are attached to the lower end of the boom as indicated. The pulley is massless and frictionless. The tension force T of the horizontal guy wire has magnitude:

A uniform plank XY is supported by two equal 120-N forces at X and Y, as shown. The support at X is then moved to Z (half-way to the plank center). The supporting forces at Y and Z are then:

The 600-N ball shown is suspended on a string AB and rests against the frictionless vertical wall. The string makes an angle of 30 °\degree° with the wall. The ball presses against the wall with a force of magnitude:

A net torque applied to a rigid object always tends to produce:

The bulk modulus is a proportionality constant that relates the pressure acting on an object to:

A 240-N weight is hung from two ropes as shown. The tension in the horizontal rope has magnitude:

A uniform 240-g meter stick can be balanced by a 240-g weight placed at the 100-cm mark if the fulcrum is placed at the point marked:

An 80-N uniform plank leans against a frictionless wall as shown. The torque (about point P) applied to the plank by the wall is:

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

An 800-N man stands halfway up a 5.0 m ladder of negligible weight. The base of the ladder is 3.0 m from the wall as shown. Assuming that the wall-ladder contact is frictionless, the wall pushes against the ladder with a force of:

A 160-N child sits on a light swing and is pulled back and held with a horizontal force of 100 N. The magnitude of the tension force of each of the two supporting ropes is:

A cube with 2.0-cm sides is made of material with a bulk modulus of 4.7 *105 N/m2. When it is subjected to a pressure of 2.0 * 105 Pa the length in cm of its any of its any of its sides is:

Stress can be measured in:

A picture P of weight W is hung by two strings as shown. The magnitude of the tension force of each string is T. The total upward pull of the strings on the picture is:

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A cube with edges exactly 2 cm long is made of material with a bulk modulus of 3.5 * 10⁹ N/m². When it is subjected to a pressure of 3.0 *10⁵ Pa its volume is:

A cube with 2.0-cm sides is made of material with a bulk modulus of 4.7 10⁵ N/m². When it is subjected to a pressure of 2.0 10⁵ Pa the length in cm of its any of its any of its sides is: