Question 1

Stress is proportional to strain means that

Accepted Answer

A) stress = constant × strain. 
B) stress = (constant 1)× strain + constant 2. 
C) stress =   . 
D) stress =   . 
E) stress × strain = constant. 
A) stress = constant × strain. 
B) stress = (constant 1)× strain + constant 2. 
C) stress =   . 
D) stress =   . 
E) stress × strain = constant. A

Question 2

A uniform 100-lb beam is held in a vertical position by a pin at its lower end and a cable at its upper end.A horizontal force (magnitude P)acts as shown in the figure.If P = 75 lb,what is the tension in the cable?

Accepted Answer

A) 54 lb 
B) 69 lb 
C) 47 lb 
D) 61 lb 
E) 75 lb 
A) 54 lb 
B) 69 lb 
C) 47 lb 
D) 61 lb 
E) 75 lb A

Question 3

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)

Accepted Answer

340 m

Question 4

Exhibit 12-1
A square of side   is removed from one corner of a square sandwich that has sides of length L.The center of mass of the remainder of the sandwich moves from C to C'.   Use this exhibit to answer the following question(s).
-Refer to Exhibit 12-1.The distance from C to C' is

Accepted Answer

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

Question 5

A uniform ladder 15 ft long is leaning against a frictionless wall at an angle of 53° above the horizontal.The weight of the ladder is 30 pounds.A 75-lb boy climbs 6.0-ft up the ladder.What is the magnitude of the friction force exerted on the ladder by the floor?

Accepted Answer

A) 43 lb 
B) 34 lb 
C) 38 lb 
D) 47 lb 
E) 24 lb 
A) 43 lb 
B) 34 lb 
C) 38 lb 
D) 47 lb 
E) 24 lb

Question 6

Exhibit 12-1
A square of side   is removed from one corner of a square sandwich that has sides of length L.The center of mass of the remainder of the sandwich moves from C to C'.   Use this exhibit to answer the following question(s).
-Refer to Exhibit 12-1.The displacement of the x coordinate of the center of mass (from C to C')is

Accepted Answer

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

Question 7

A horizontal uniform 1.20-N meter stick is held up by two vertical strings,one at the 20-cm mark and the other at the 60-cm mark.What is the tension in the string at the 60-cm mark?

Accepted Answer

A) 0.30 N 
B) 0.45 N 
C) 0.60 N 
D) 0.90 N 
E) 1.0 N 
A) 0.30 N 
B) 0.45 N 
C) 0.60 N 
D) 0.90 N 
E) 1.0 N

Question 8

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

Question 9

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

Question 10

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

Accepted Answer

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

Question 11

Find the minimum diameter of a steel wire 18 m long that will stretch no more than 9 mm when a load of 380 kg is hung on the lower end.(Y steel = 2.0 × 1011 N/m2).

Accepted Answer

Question 12

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

Question 13

A non-uniform meter stick is found to balance on a knife edge at the 60-cm mark.Where is the center of gravity of the meter stick?

Accepted Answer

A) at the 40-cm mark 
B) at the 45-cm mark 
C) at the 50-cm mark 
D) at the 55-cm mark 
E) at a position not given 
A) at the 40-cm mark 
B) at the 45-cm mark 
C) at the 50-cm mark 
D) at the 55-cm mark 
E) at a position not given

Question 14

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 a...

Question 15

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. 
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 16

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

Question 17

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. 
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 18

The center of gravity of an object is at the same position as the center of mass when

Accepted Answer

A)    is the same at both ends of the object. 
B) the object is located in a region where   is uniform over the entire object. 
C) the object is as large as the body that exerts the gravitational force on it. 
D) any of the conditions above is satisfied. 
E) either (a)or (b)above is satisfied. 
A)    is the same at both ends of the object. 
B) the object is located in a region where   is uniform over the entire object. 
C) the object is as large as the body that exerts the gravitational force on it. 
D) any of the conditions above is satisfied. 
E) either (a)or (b)above is satisfied.

Question 19

Exhibit 12-1
A square of side   is removed from one corner of a square sandwich that has sides of length L.The center of mass of the remainder of the sandwich moves from C to C'.   Use this exhibit to answer the following question(s).
-Refer to Exhibit 12-1.The displacement of the y coordinate of the center of mass (from C to C')is

Accepted Answer

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

Question 20

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

Exam 12: Static Equilibrium and Elasticity

Stress is proportional to strain means that

A uniform 100-lb beam is held in a vertical position by a pin at its lower end and a cable at its upper end.A horizontal force (magnitude P)acts as shown in the figure.If P = 75 lb,what is the tension in the cable?

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)

Exhibit 12-1 A square of side is removed from one corner of a square sandwich that has sides of length L.The center of mass of the remainder of the sandwich moves from C to C'. Use this exhibit to answer the following question(s). -Refer to Exhibit 12-1.The distance from C to C' is

A uniform ladder 15 ft long is leaning against a frictionless wall at an angle of 53° above the horizontal.The weight of the ladder is 30 pounds.A 75-lb boy climbs 6.0-ft up the ladder.What is the magnitude of the friction force exerted on the ladder by the floor?

A horizontal uniform 1.20-N meter stick is held up by two vertical strings,one at the 20-cm mark and the other at the 60-cm mark.What is the tension in the string at the 60-cm mark?

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.

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?

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

Find the minimum diameter of a steel wire 18 m long that will stretch no more than 9 mm when a load of 380 kg is hung on the lower end.(Y steel = 2.0 × 1011 N/m2).

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.

A non-uniform meter stick is found to balance on a knife edge at the 60-cm mark.Where is the center of gravity of the meter stick?

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.

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 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?

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?

The center of gravity of an object is at the same position as the center of mass when

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?

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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)

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.

Find the minimum diameter of a steel wire 18 m long that will stretch no more than 9 mm when a load of 380 kg is hung on the lower end.(Y steel = 2.0 × 10¹¹ N/m²).

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.