Question 1

The diagrams below show forces of magnitude F applied to an equilateral triangular block of uniform thickness. In which diagram(s) is(are) the block in equilibrium?

Accepted Answer

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

Question 2

Pairs of forces of equal magnitude act on identical cylinders as shown in the figures. In which example is the cylinder in translational and rotational equilibrium?

Accepted Answer

A)   
B)   
C)   
D)   
E)

Question 3

The diagrams below show forces applied to a wheel that weighs 20 N. The symbol W stands for the weight. In which diagram(s) is(are) the wheel in equilibrium?

Accepted Answer

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

Question 4

How large a pressure increase (in atm) must be applied to water if it is to be compressed in volume by 1.0%? The bulk modulus of water is 2.0 × 109 N/m2 and 1 atm = 1.0 × 105 N/m2.

Accepted Answer

A) 50 atm 
B) 100 atm 
C) 1 100 atm 
D) 400 atm 
E) 200 atm

Question 5

Which one of the following cannot be a definition of an elastic modulus?

Accepted Answer

A)   
B)   
C)   
D)   
E)

Question 6

A mobile is made of identical objects of mass m suspended so that the lowest row has one object, the row above two objects, and the row above three objects. All the strings are at 45° angles. What is the average tension in the strings connecting the highest row to the ceiling?

Accepted Answer

A)   
B)   
C) mg 
D)   
E)

Question 7

A uniform 120-lb beam is supported in a horizontal position by a pin and cable as shown in the figure. What is the magnitude of the force by the pin on the beam?

Accepted Answer

A) 94 lb 
B) 88 lb 
C) 63 lb 
D) 75 lb 
E) 150 lb

Question 8

For safety in climbing, a mountaineer uses a 50-m long nylon rope that is 1.0 cm in diameter. When supporting a 90-kg climber, the rope elongates 1.6 m. Find the Young's modulus for the rope material.

Accepted Answer

The answer of For safety in climbing, a mountaineer uses...

Question 9

If 1.0 m³ of concrete weighs 5 × 10⁴ N, what is the height of the tallest cylindrical concrete pillar that will not collapse under its own weight? (The compression strength of concrete is 1.7 × 10⁷N/m².)

Accepted Answer

The answer of If 1.0 m³ of concrete weighs 5...

Question 10

How large a force is necessary to stretch a 2.0-mm diameter copper wire (Y = 11 × 1010 N/m2) by 1.0%?

Accepted Answer

A) 2.1 kN 
B) 3.5 kN 
C) 6.9 kN 
D) 11 kN 
E) 5.4 kN

Question 11

The four tires of an automobile are inflated to a gauge pressure of 2.0 × 10⁵ N/m² (29 PSI). Each of the four tires has an area of 0.024 m² that is in contact with the ground. Determine the weight of the auto.

Accepted Answer

The answer of The four tires of an automobile are...

Question 12

Sebastian has drawn a free-body diagram for a ladder of mass m leaning against a frictionless wall. His diagram is shown below. What is his error? ​  ​

Accepted Answer

A)   is in the wrong direction. 
B)   should be directed upwards, not down. 
C)   should be perpendicular to the wall, not parallel to it. 
D)   should be down into the floor for  to have the given direction. 
E)   is correct, but there should also be a force perpendicular to the wall.

Question 13

Angie says that an object is in equilibrium if the net torques about the center of mass is zero. Robbie says that an object is in equilibrium if the sum of external forces is zero. Which one, if either, is correct?

Accepted Answer

A) Both are correct: an object is in equilibrium if either condition holds. 
B) Neither is correct: both conditions must hold simultaneously. 
C) Neither is correct: the net external force and the net external torque about any axis must be zero. 
D) Neither is correct: an object is in equilibrium only if its velocity is zero in all coordinate systems. 
E) Both are correct: if the sum of the external forces is zero, the net torque about any axis is automatically zero, and vice versa.

Question 14

The 1560-kg solid steel door to a bank vault is 2.00 m high, 1.00-m wide and 10-cm thick. One hinge is 60.0 cm down from the top on the left-hand side of the door. The other hinge is 30.0 cm up from the bottom. What horizontal force, in what direction, does the door exert on the lower hinge?

Accepted Answer

A) 6950 N, left 
B) 6950 N, right 
C) 7640 N, left 
D) 7640 N, right 
E) 15,300 N, left

Exam 14: Static Equilibrium, Elasticity, and Fracture

The diagrams below show forces of magnitude F applied to an equilateral triangular block of uniform thickness. In which diagram(s) is(are) the block in equilibrium?

Pairs of forces of equal magnitude act on identical cylinders as shown in the figures. In which example is the cylinder in translational and rotational equilibrium?

The diagrams below show forces applied to a wheel that weighs 20 N. The symbol W stands for the weight. In which diagram(s) is(are) the wheel in equilibrium?

How large a pressure increase (in atm) must be applied to water if it is to be compressed in volume by 1.0%? The bulk modulus of water is 2.0 × 10⁹ N/m² and 1 atm = 1.0 × 10⁵ N/m².

Which one of the following cannot be a definition of an elastic modulus?

A mobile is made of identical objects of mass m suspended so that the lowest row has one object, the row above two objects, and the row above three objects. All the strings are at 45° angles. What is the average tension in the strings connecting the highest row to the ceiling?

A uniform 120-lb beam is supported in a horizontal position by a pin and cable as shown in the figure. What is the magnitude of the force by the pin on the beam?

For safety in climbing, a mountaineer uses a 50-m long nylon rope that is 1.0 cm in diameter. When supporting a 90-kg climber, the rope elongates 1.6 m. Find the Young's modulus for the rope material.

If 1.0 m³ of concrete weighs 5 × 10⁴ N, what is the height of the tallest cylindrical concrete pillar that will not collapse under its own weight? (The compression strength of concrete is 1.7 × 10⁷N/m².)

How large a force is necessary to stretch a 2.0-mm diameter copper wire (Y = 11 × 10¹⁰ N/m²) by 1.0%?

The four tires of an automobile are inflated to a gauge pressure of 2.0 × 10⁵ N/m² (29 PSI). Each of the four tires has an area of 0.024 m² that is in contact with the ground. Determine the weight of the auto.

Sebastian has drawn a free-body diagram for a ladder of mass m leaning against a frictionless wall. His diagram is shown below. What is his error?

Angie says that an object is in equilibrium if the net torques about the center of mass is zero. Robbie says that an object is in equilibrium if the sum of external forces is zero. Which one, if either, is correct?

The 1560-kg solid steel door to a bank vault is 2.00 m high, 1.00-m wide and 10-cm thick. One hinge is 60.0 cm down from the top on the left-hand side of the door. The other hinge is 30.0 cm up from the bottom. What horizontal force, in what direction, does the door exert on the lower hinge?

Exam 14: Static Equilibrium, Elasticity, and Fracture

The diagrams below show forces of magnitude F applied to an equilateral triangular block of uniform thickness. In which diagram(s) is(are) the block in equilibrium?

Pairs of forces of equal magnitude act on identical cylinders as shown in the figures. In which example is the cylinder in translational and rotational equilibrium?

The diagrams below show forces applied to a wheel that weighs 20 N. The symbol W stands for the weight. In which diagram(s) is(are) the wheel in equilibrium?

How large a pressure increase (in atm) must be applied to water if it is to be compressed in volume by 1.0%? The bulk modulus of water is 2.0 × 109 N/m2 and 1 atm = 1.0 × 105 N/m2.

Which one of the following cannot be a definition of an elastic modulus?

A mobile is made of identical objects of mass m suspended so that the lowest row has one object, the row above two objects, and the row above three objects. All the strings are at 45° angles. What is the average tension in the strings connecting the highest row to the ceiling?

A uniform 120-lb beam is supported in a horizontal position by a pin and cable as shown in the figure. What is the magnitude of the force by the pin on the beam?

For safety in climbing, a mountaineer uses a 50-m long nylon rope that is 1.0 cm in diameter. When supporting a 90-kg climber, the rope elongates 1.6 m. Find the Young's modulus for the rope material.

If 1.0 m3 of concrete weighs 5 × 104 N, what is the height of the tallest cylindrical concrete pillar that will not collapse under its own weight? (The compression strength of concrete is 1.7 × 107 N/m2.)

How large a force is necessary to stretch a 2.0-mm diameter copper wire (Y = 11 × 1010 N/m2) by 1.0%?

The four tires of an automobile are inflated to a gauge pressure of 2.0 × 105 N/m2 (29 PSI). Each of the four tires has an area of 0.024 m2 that is in contact with the ground. Determine the weight of the auto.

Sebastian has drawn a free-body diagram for a ladder of mass m leaning against a frictionless wall. His diagram is shown below. What is his error? ​ ​

Angie says that an object is in equilibrium if the net torques about the center of mass is zero. Robbie says that an object is in equilibrium if the sum of external forces is zero. Which one, if either, is correct?

The 1560-kg solid steel door to a bank vault is 2.00 m high, 1.00-m wide and 10-cm thick. One hinge is 60.0 cm down from the top on the left-hand side of the door. The other hinge is 30.0 cm up from the bottom. What horizontal force, in what direction, does the door exert on the lower hinge?

How large a pressure increase (in atm) must be applied to water if it is to be compressed in volume by 1.0%? The bulk modulus of water is 2.0 × 10⁹ N/m² and 1 atm = 1.0 × 10⁵ N/m².

If 1.0 m³ of concrete weighs 5 × 10⁴ N, what is the height of the tallest cylindrical concrete pillar that will not collapse under its own weight? (The compression strength of concrete is 1.7 × 10⁷N/m².)

How large a force is necessary to stretch a 2.0-mm diameter copper wire (Y = 11 × 10¹⁰ N/m²) by 1.0%?

The four tires of an automobile are inflated to a gauge pressure of 2.0 × 10⁵ N/m² (29 PSI). Each of the four tires has an area of 0.024 m² that is in contact with the ground. Determine the weight of the auto.

Sebastian has drawn a free-body diagram for a ladder of mass m leaning against a frictionless wall. His diagram is shown below. What is his error?