Question 1

Stress has dimensions of

Accepted Answer

A)  force multiplied by area. 
B)  force divided by area. 
C)  force divided by length. 
D)  none of the above. 
A)  force multiplied by area. 
B)  force divided by area. 
C)  force divided by length. 
D)  none of the above. B

Question 2

If the mechanical advantage of a system is > 1, then

Accepted Answer

A) the applied force is > the delivered force. B) the applied force is = the delivered force. C) the applied force is < the delivered force. D) none of the above. A) the applied force is > the delivered force. B) the applied force is = the delivered force. C) the applied force is < the delivered force. D) none of the above. C

Question 3

A metal cube, 5 cm on edge, undergoes a shearing force of 14,000 N (on opposing ends). If the shear modulus is $9 \times 10 ^ { 10 }$ Pa, the distance that the cube is sheared is

Accepted Answer

A)  $7.5 \mu$ m. 
B)  $4.4 \mu$ m. 
C)  $3.1 \mu$ m. 
D)  $5.6 \mu$ m. 
A)  $7.5 \mu$ m. 
B)  $4.4 \mu$ m. 
C)  $3.1 \mu$ m. 
D)  $5.6 \mu$ m. C

Question 4

The density of a material must change when the material is subjected to

Accepted Answer

A)  shear forces. 
B)  elongation forces. 
C)  compression forces. 
D)  none of the above. 
A)  shear forces. 
B)  elongation forces. 
C)  compression forces. 
D)  none of the above.

Question 5

In SI units, the dimensions of the various sorts of modulus are

Accepted Answer

A)  Newton-meters2. 
B)  Newton-meters. 
C)  Newtons/meter. 
D)  Newtons/meter2. 
A)  Newton-meters2. 
B)  Newton-meters. 
C)  Newtons/meter. 
D)  Newtons/meter2.

Question 6

A tightrope walker weighing 950 N stands in the middle of a tightrope that is 10 m long. The tension in the tightrope so that the walker has deflected the tightrope downward by only 1 cm is

Accepted Answer

A)  240,000 N. 
B)  18,000 N. 
C)  9500 N. 
D)  51,000 N. 
A)  240,000 N. 
B)  18,000 N. 
C)  9500 N. 
D)  51,000 N.

Question 7

Five cubes (each edge of a cube is 5 cm) are stacked vertically on a table. If each cube weighs 5 N, the pressure exerted on the table is

Accepted Answer

A)  1 Pa. 
B)  20 Pa. 
C)  10 kPa. 
D)  100 Pa. 
A)  1 Pa. 
B)  20 Pa. 
C)  10 kPa. 
D)  100 Pa.

Question 8

A 0.75-m-long piano wire (radius of 0.5 mm) has one end fixed and the other end attached to a rotatable tuning peg (having a radius of 2 mm). The tuning peg is rotated so that the wire is just taut, and then the peg is given three full turns (tightening the wire). If the Young's modulus is $2 \times 10 ^ { 11 }$ Pa, the tension in the piano wire is

Accepted Answer

A)  7900 N. 
B)  6600 N. 
C)  5600 N. 
D)  4400 N. 
A)  7900 N. 
B)  6600 N. 
C)  5600 N. 
D)  4400 N.

Question 9

A 5-m-long steel cable is horizontally attached (just tautly) between two large trees. A 40-kg child hangs from the middle, and in doing so lowers the cable 6 cm from its original position. If the Young's modulus of the steel cable is $1 \times 10 ^ { 11 }$ Pa and the cross-sectional area is 0.7 cm $2$ , the distance that the steel cable is stretched is

Accepted Answer

A)  6 mm. 
B)  6 m. 
C)  6 cm. 
D)  0.6 m. 
A)  6 mm. 
B)  6 m. 
C)  6 cm. 
D)  0.6 m.

Question 10

The shape of a body must change for each of the following forces except

Accepted Answer

A)  shear forces. 
B)  elongation forces. 
C)  compression forces. 
D)  none of the above. 
A)  shear forces. 
B)  elongation forces. 
C)  compression forces. 
D)  none of the above.

Question 11

A 4-m-long ladder (mass = 56 kg) leans against a frictionless wall. The base of the ladder makes an angle of 55(which is not the maximum frictional force) with the rough floor, having $\mu _ { s } = 0.5$ . The upward vertical force exerted by the floor that acts on the ladder is

Accepted Answer

A)  270 N. 
B)  550 N. 
C)  230 N. 
D)  190 N. 
A)  270 N. 
B)  550 N. 
C)  230 N. 
D)  190 N.

Question 12

All of the following properties of a body have the same dimensions except

Accepted Answer

A)  Young's modulus. 
B)  elastic limit. 
C)  ultimate strength. 
D)  shear modulus. 
A)  Young's modulus. 
B)  elastic limit. 
C)  ultimate strength. 
D)  shear modulus.

Question 13

An I-beam having a mass of 810 kg and length of 5.1 m has one end attached to a vertical wall. The I-beam is allowed to pivot up and down about the attachment location. A cable is then attached from the vertical wall to the other end of the I-beam. The cable makes an angle of 31º with the I-beam, and the I-beam is horizontal (parallel with the ground). The horizontal pin force at the pivot is

Accepted Answer

A)  8100 N. 
B)  4200 N. 
C)  6600 N. 
D)  3800 N. 
A)  8100 N. 
B)  4200 N. 
C)  6600 N. 
D)  3800 N.

Question 14

A dimensionless quantity is

Accepted Answer

A)  strain. 
B)  mechanical advantage. 
C)  Both of the first two answers are valid. 
D)  Neither of the first two answers is valid. 
A)  strain. 
B)  mechanical advantage. 
C)  Both of the first two answers are valid. 
D)  Neither of the first two answers is valid.

Question 15

Consider a truss designed to support some maximum weight W on a frictionless, horizontal surface. The truss has three straight members joined as in the letter "A," and all members of the truss are weightless. W is placed at the apex of the truss. A single modification that would permit stable support of a weight heavier than W for a given strength of the horizontal cross member is to

Accepted Answer

A)  move the horizontal cross member toward the apex of the truss. 
B)  move the horizontal cross member toward the floor. 
C)  move the horizontal cross member to the exact midpoint of the distance from apex to floor. 
D)  none of the above. 
A)  move the horizontal cross member toward the apex of the truss. 
B)  move the horizontal cross member toward the floor. 
C)  move the horizontal cross member to the exact midpoint of the distance from apex to floor. 
D)  none of the above.

Question 16

An I-beam having a mass of 810 kg and length of 5.1 m has one end attached to a vertical wall, the I-beam is allowed to pivot up and down about the attachment location. A cable is then attached from the vertical wall to the other end of the I-beam. The cable makes an angle of 31º with the I-beam, and the I-beam is horizontal (parallel with the ground). The vertical pin force at the pivot is

Accepted Answer

A)  8100 N. 
B)  4000 N. 
C)  6000 N. 
D)  3000 N. 
A)  8100 N. 
B)  4000 N. 
C)  6000 N. 
D)  3000 N.

Question 17

The maximum number of independent equations that must be satisfied for static equilibrium for a rigid body is

Accepted Answer

A)  2. 
B)  3. 
C)  4. 
D)  6. 
A)  2. 
B)  3. 
C)  4. 
D)  6.

Question 18

The proper relation between stress and strain is

Accepted Answer

A)  stress = strain. 
B)  stress = l/strain. 
C)  Stress ? strain. 
D)  Stress ? l/strain. 
A)  stress = strain. 
B)  stress = l/strain. 
C)  Stress ? strain. 
D)  Stress ? l/strain.

Question 19

Water has a bulk modulus of $0.2 \times 10 ^ { 10 }$ Pa. The pressure required to compress a volume of liquid water by 1% is

Accepted Answer

A)  20 MPa. 
B)  10 KPa. 
C)  10 MPa. 
D)  20 KPa. 
A)  20 MPa. 
B)  10 KPa. 
C)  10 MPa. 
D)  20 KPa.

Question 20

A ladder of length $l$ and mass $= m$ leans against a frictionless wall. The base of the ladder makes an angle $\theta$ with the rough floor, $\mu _ { s }$. Providing that the ladder is in static equilibrium, the relation between $\theta$ and $\mu _ { s }$ is

Accepted Answer

A)  $2 \mu \tan \theta = 1$ 
B)  $2 \mu = m g \cos \theta$ 
C)  $\mu = 2 \theta$ 
D)  $\tan \theta = \mu$ 
A)  $2 \mu \tan \theta = 1$ 
B)  $2 \mu = m g \cos \theta$ 
C)  $\mu = 2 \theta$ 
D)  $\tan \theta = \mu$

Exam 14: Statics and Elasticity

Stress has dimensions of

If the mechanical advantage of a system is > 1, then

A metal cube, 5 cm on edge, undergoes a shearing force of 14,000 N (on opposing ends). If the shear modulus is 9×10109 \times 10 ^ { 10 }9×1010 Pa, the distance that the cube is sheared is

The density of a material must change when the material is subjected to

In SI units, the dimensions of the various sorts of modulus are

A tightrope walker weighing 950 N stands in the middle of a tightrope that is 10 m long. The tension in the tightrope so that the walker has deflected the tightrope downward by only 1 cm is

Five cubes (each edge of a cube is 5 cm) are stacked vertically on a table. If each cube weighs 5 N, the pressure exerted on the table is

The shape of a body must change for each of the following forces except

A 4-m-long ladder (mass = 56 kg) leans against a frictionless wall. The base of the ladder makes an angle of 55(which is not the maximum frictional force) with the rough floor, having μs=0.5\mu _ { s } = 0.5μs​=0.5 . The upward vertical force exerted by the floor that acts on the ladder is

All of the following properties of a body have the same dimensions except

A dimensionless quantity is

The maximum number of independent equations that must be satisfied for static equilibrium for a rigid body is

The proper relation between stress and strain is

Water has a bulk modulus of 0.2×10100.2 \times 10 ^ { 10 }0.2×1010 Pa. The pressure required to compress a volume of liquid water by 1% is

A ladder of length lll and mass =m= m=m leans against a frictionless wall. The base of the ladder makes an angle θ\thetaθ with the rough floor, μs\mu _ { s }μs​ . Providing that the ladder is in static equilibrium, the relation between θ\thetaθ and μs\mu _ { s }μs​ is

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A metal cube, 5 cm on edge, undergoes a shearing force of 14,000 N (on opposing ends). If the shear modulus is $9 \times 10 ^ { 10 }$ Pa, the distance that the cube is sheared is

A 4-m-long ladder (mass = 56 kg) leans against a frictionless wall. The base of the ladder makes an angle of 55(which is not the maximum frictional force) with the rough floor, having $\mu _ { s } = 0.5$ . The upward vertical force exerted by the floor that acts on the ladder is

Water has a bulk modulus of $0.2 \times 10 ^ { 10 }$ Pa. The pressure required to compress a volume of liquid water by 1% is

A ladder of length $l$ and mass $= m$ leans against a frictionless wall. The base of the ladder makes an angle $\theta$ with the rough floor, $\mu _ { s }$ . Providing that the ladder is in static equilibrium, the relation between $\theta$ and $\mu _ { s }$ is