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Quiz

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School
Western University
Department
Physics
Course
Physics 1021
Professor
Lara Braitstein
Semester
Winter

Description
RM QUIZ 14 AND 15 (MC-12-WN-001) An object is attached to a horizontal spring. It is initially displaced by a given distance from the equilibrium position (index 1). If I double the displacement (index 2), the elastic energy of the object changes from E1 to E2, where: A. ... E2 = E1, i.e., energy is conserved B. ... E2 = 0.5 E1 C. ... E2 = 2 E1 D. ... E2 = 0.25 E1 E. ... E2 = 4 E1 (MC-12-WN-002) An object is attached to a horizontal spring. It is initially displaced by distance Δx from the equilibrium position and then released from rest. At what point of its motion along the x-axis reaches the object its highest potential energy? A. At the equilibrium position B. At the position where it is released C. At midway between the amplitude and equilibrium positions D. The potential energy is the same at all positions E. The object reaches its highest potential energy only during a later cycle, not during the first oscillation (MC-12-WN-003) An object is attached to a horizontal spring. It is initially displaced by dΔsx from the equilibrium position and then released from rest. At what point of its motion along the x-axis reaches the object its highest total energy? A. At the equilibrium position B. At the position where it is released C. At midway between the amplitude and equilibrium positions D. The total energy is the same at all positions E. The object reaches its highest total energy only during a later cycle, not during the first oscillation (MC-12-WN-004) An object is attached to a horizontal spring. It is initially displaced by distance Δx from the equilibrium position and then released from rest. When the object passes the equilibrium position, its speed will be: A. v = 0 m/s B. proportional to Δx (the speed is proportional to the initial displacement) C. proportional to Δx2 (speed is proportional to the square of the initial displacement) D. is a non-linear function of the Δx, but cannot be written in the form Δv proportional to Δx2 (MC-12-WN-005) An object is attached to a horizontal spring. The equilibrium position of the object is at position x = xeq. The elastic force due to the spring is written as: Felast = - k(x - xeq) What does the negative sign in front of the bracket on the right hand side imply? A. The object is in mechanical equilibrium B. The elastic force is a restoring force C. The object displays cyclic motion D. The object displays a sinusoidal motion E. The energy of the system is conserved (MC-12-WN-006) The attached figure shows a mobile piston that seals a gas in a horizontal cylinder. The piston is in mechanical equilibrium at position xeq where the gas pressure pgas is equal to the external atmospheric pressure patm. An external force allows us to move the piston to a new position at xeq - x. The origin of the x-axis is chosen at the left end of the gas cylinder. Which statement is incorrect regarding the lower part of the figure? A. The piston is in mechanical equilibrium B. When released (Fext removed) the piston travels toward smaller x-values C. After release, an ideal (frictionless) piston will move back and forth in a harmonic fashion D. Immediately after the piston is released, the gas expands E. Immediately after the piston is released, the gas does work on the piston (MC-12-WN-007) Consider the elastic force equation: Felast = -k (x-xeq) What does the negative sign in the bracket on the right hand side imply? A. The force is proportional to the displacement B. The equilibrium position lies at a positive x position C. The object is located at the equilibrium position D. The forces increases when the object moves to positive x-values E. The energy of the system is conserved (MC-12-WN-008) The attached figure shows the potential energy as a function of distance between a Na+ ion and a Cl- ion in rock salt (NaCl). The electrostatic attraction between the ions is the red curve at negative energies, the repulsive energy is the red curve at positive energies. The combined potential energy curve for the NaCl bond is shown as an asymmetric blue curve. A. The blue line represents the potential energy curve for a harmonic oscillator B. The red line labelled "electrostatic" represents the potential energy curve for a harmonic oscillator C. The red line labelled "replusive" represents the potential energy curve for a harmonic oscillator D. Only the lower part of the blue curve can be modeled (approximately) as the potential energy of a harmonic oscillator E. The harmonic oscillator model cannot be used to describe the NaCl bond in rock salt (MC-12-WD-001) The attached figure shows the stress-strain relation for steel. Up to which stress value does the strain in steel respond linearly to the exerted stress? (Choose closest value) A. σ = 0 Pa B. ε = 30 % C. σ = 3.5 x 108 Pa D. ε = 4 % E. σ = 2 x 108 Pa (MC-12-WD-002) Comparing the two attached figures, the following statement is correct: A. Both steel and blood vessels require roughly the same strain for a given stress B. Hooke's law can be applied to both systems C. Due to the differences in stress for a given strain, steel is called a hard material and blood vessel tissue is called a soft material D. Steels ruptures at much larger strain values than blood vessel tissue E. None of the statements is correct (MC-12-WD-003) The attached figure shows the stress-strain relation for the elastic tissue of blood vessels. The blood vessel contains two components which play a role in its elastic properties: elastin (dash-dotted curve) and collagen with a bulk modulus increasing with strain (dashed curve). These contributions are combined (solid curve) for an actual blood vessel. Based on the figure, which of the following statements is true? A. The elastic properties of elastin cannot be described by Hooke's law B. Collagen shows a linear stress-strain behaviour up to strains of 100% C. Collagen shows a linear stress-strain behaviour up to strains of about 50% D. The actual blood vessel wall shows no linear stress-strain behaviour due to its collagen component E. The actual blood vessel wall shows no linear stress-strain behaviour due to its elastin component RM QUIZ 16 (MC-09-QA-001) A Na+ ion in an aqueous rock salt solution diffuses relatively slowly because: A. Too many chlorine ions are in its close vicinity B. Neutral NaCl molecules block its diffusion C. It has to drag its hydration shell along D. Buoyancy limits its motion in the direction toward the surface E. It has to drag a nearby chlorine ion along (MC-09-QA-002) A hydrogen bond has the following property: A. It connects two hydrogen atoms between two different molecules B. It connects two hydrogen atoms within the same molecule C. It is a covalent bond between hydrogen and oxygen or nitrogen D. It is weaker than a covalent bond, acting between hydrogen and oxygen or nitrogen, respectively E. It is only a way to express that a hydrogen atom is close to an oxygen or nitrogen atom, but does not exist as a physical bond (MC-09-QA-003) The water molecule is shown in the attached figure. Based on the water molecule in this figure of a dipole, the electric field associated with the net negative and positive charges points in the following direction: A. To the left B. To the right C. Up D. Down E. No electric field can be identified in the water molecule (MC-09-QA-004) The electric dipole moment is calculated aμ = qd in which q is the charge separated in the dipole and d is the distance to which the charges are separated. Which of the following statementsμais wrong? A. A molecule is a strong dipole if a large amount of net charge is separated in the molecule. B. A molecule is a strong dipole if the net charge separation occurs over a short distance within the molecule C. The unit oμ is [C · m] D. A dipole can exert a force on a charged particle at close proximity E. A dipole can exert a force on another dipole at close proximity o (MC-09-QA-005) The two OH-bonds in the water molecule are arranged at an angle of 104.5 . At what angle between these bonds would the water molecule no longer be a dipole? A. Any angle other then 104.5 B. The molecule is a dipole at any angle o C. At 180 o D. At 0 o E. At 90 (MC-09-QC-001) A hydrogen atom consists of a positively charged proton (nucleus) and a negatively charged electron. The following is correct due to Coulomb's law: A. The two particles repel each other B. The electron accelerates toward the proton C. The electron and proton are in mechanical equilibrium, thus no net force acts between them D. None of these statements is correct (MC-09-QC-002) In part (a) of the attached figure we study two identical, electrically isolated spheres A and B. The surface of each sphere is conducting which allows for a uniform charge distribution. The spheres are separated by a distance x that is large compared to the diameter of each of the two spheres. Sphere A has initially a positive charge of +q and sphere B is electrically neutral (q = 0). Thus, there is no 0 electrostatic force acting between the spheres. Suppose the spheres are now connected with a conducting wire as shown in part (b) of the attached figure. We assume that the wire is thin enough so that any net charge on it can be neglected. However, the repulsive force between the charges on sphere A leads to an equal distribution of charges between the two spheres, i.e., all the charges move to a maximum mutual distance. What is the electrostatic force between the spheres after the wire is removed? 2 A. (1/4πε )0(q /0x) 2 B. (1/4πε 0 (Q/2a) 2 C. (1/4πε 0 (q 0x) 2 D. (1/4πε )0(Q/a) 2 E. (1/16πε )0(q /0x) 2 F. (1/16πε )0(Q/2a) 3 G. (1/4πε )0(q /0x) 3 H. (1/4πε )0(Q/2a) (MC-09-QC-003) Two charged particles attract each other with an electric force of magnitude F . If we do0ble the charge on each of the particles, the force between the particles becomes ... A. F0/4 B. F0/2 C. 2 F 0 D. 4 F 0 E. 8 F0 (MC-09-QC-004) Two charged particles attract each other with an electric force of magnitude F . If we double the 0 distance between the particles, the force between the particles becomes... A. F0/4 B. F0/2 C. 2 F 0 D. 4 F 0 E. 8 F0 RM QUIZ 17 (MC-09-QF-002) Near an isolated negative charge the electric field is directed ... A. ... toward the negative charge B. ... away from the negative charge C. ... in a direction we can only determine if we know where the closest positive charge is located D. ... perpendicular to a line through the negative charge E. None of the above statements (A) through (D) is correct (MC-09-QF-003) The electric field across a nerve membrane has a value of about 8 x 10 N/C. This is a comparably large electric field. The field is large because ... A. ... the surface charge density on the nerve membrane is low B. ... charges are located well separated from each other across the surface of the nerve membrane C. ... the membrane in very thin D. ... a large electric potential exists across the nerve membrane E. ... ions in the axoplasm and the extracellular fluid enhance the effect of the charges located on the nerve membrane by forming dipoles (MC-09-QF-005) The electric field is constant in magnitude and direction for the following arrangement of fixed charges: A. Close to a point charge B. Close to a dipole C. Far from a dipole, i.e., at a distance greater than 10 times the charge separation distance d of the dipole D. In the vicinity of a pair of charged parallel plates E. Between two charged parallel plates -31 -27 (MC-09-QF-006) The mass of the electron is 9.11 x 10 kg and the mass of the proton is 1.67 x 10 kg. Both carry the same elementary charge (positive for the proton and negative for the electron). If I release both particles from rest at the middle point between two charged parallel plates in vacuum, which of the following is true? A. Both reach the respectively oppositely charged plate at the same time B. The electron strikes the positive plate first C. The proton strikes the positive plate first D. The electron strikes the negative plate first E. The proton strikes the negative plate first (MC-09-QF-007) We consider a single, positive point charge. For this point charge, the electric field ... A. ... is constant as a function of distance from the point charge B. ... decreases linearly with distance from the point charge C. ... increases linearly with distance from the point charge D. ... decreases quadratically with distance from the point charge E. ... increases quadratically with distance from the point charge (MC-09-QP-001) A positive sodium ion is transported across a membrane. The ion is initially located on the positive side of the membrane and reaches finally the negative side of the membrane. In this process ... A. ... has the ion moved to a higher electric potential B. ... has the ion moved to a lower electric potential C. ... does the ion not encounter a change in electric potential (MC-09-QP-002) If the electric field has a constant magnitude and points in the positive x-direction, which of the following formulas is correct to describe the potential if a, b, and c are positive non-zero constants (i.e., a >0, b >0, c > 0): A. V = a B. V = a + b x C. V = a - b x 2 D. V = a + b x + c x 2 E. V = a - b x - c x (MC-09-QP-004) The figure shows the electric potential energy as a function of position for the electron in a hydrogen atom.We consider three possible electrons with total energies E (1), E (2), and E (3). Which of the three total total total electrons remains closest to the nucleus at all times? A. All three electrons remain equally close to the nucleus all the time. B. The electron with E total).
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