Four long wires are perpendicular to the x-y plane. Each wire carries the same magnitude current. Wire 1 goes through point (a, a, 0) on the x-y plane, wire 2 goes through the point (a, a, 0), wire 3 goes through the point (a, a, 0), and wire 4 goes through the point (a, a, 0). Wires 1 and 3 carry their currents in the positive z direction and wires 2 and 4 carry their currents in the z direction. What is the direction of the resulting magnetic field at the origin?
a. in the +x direction
b. in the y direction
c. in the x direction
d. There is no direction since the field is zero at this point.
[Ques. 2] The motion of a piston in an automobile engine is nearly simple harmonic. If the 1-kg piston travels back and forth over a distance of 12.0 cm, what is its maximum speed when the engine is running at 3000 rpm?
a. 4.71 m/s
c. 44.0m/s
b. 9.42 m/s
d. 22.0 m/s
[Ques. 3] Four long wires are perpendicular to the x-y plane. Each wire carries the same magnitude current. Wire 1 goes through point (a, a, 0) on the x-y plane, wire 2 goes through the point (a, a, 0), wire 3 goes through the point (a, a, 0), and wire 4 goes through the point (a, a, 0). Wires 1 and 2 carry their currents in the positive z direction and wires 3 and 4 carry their currents in the z direction. What is the direction of the resulting magnetic field at the origin?
a. the x direction
b. the y direction
c. the +x direction
d. There is no direction since the field is zero at this position.
[Ques. 4] An object moving in simple harmonic motion has an amplitude of 0.020 m and a maximum acceleration of 20 m/s2 . What is the frequency of the system?
a. 0.40 Hz
c. 10.1 Hz
b. 5.0 Hz
d. 32 Hz
[Ques. 5] A square loop of wire has a current going around it. The magnetic field from the current on each side of the loop results in a magnetic force on the wire on the opposite side. Each resulting magnetic force on the opposite side wire
a. pushes inward on the loop.
b. is actually zero since a current cannot push on itself.
c. depends on whether the current is clockwise of counterclockwise.
d. pushes outward on the loop.
[Ques. 6] A mass on a spring vibrates in simple harmonic motion at a frequency of 4.0 Hz and an amplitude of 5.0 cm. If a timer is started when its displacement is a maximum (hence x = 5 cm when t = 0), what is the acceleration magnitude when t = 3 s?
a. 31.6 m/s2
c. 10.5 m/s2
b. 15.8 m/s2
d. zero
[Ques. 7] Two long parallel wires are a distance d apart. The current in one wire is 10 A and the current in the other wire is 30 A. The currents are in the same direction. If the 30-A current is increased to 50 A, by what factor does the magnitude of the magnetic field midway between the wires change?
a. 2
c. 25/9
b. 4
d. 5/3
[Ques. 8] For a mass suspended on a spring in the vertical direction, the time for one complete oscillation will depend on:
a. the value for g (the acceleration due to gravity).
b. the distance the mass was originally pulled down.
c. the maximum speed of the oscillating mass.
d. the time doesn't depend on any of the above.
[Ques. 9] A superconducting solenoid is to be designed to generate a magnetic field of 2.50 T. If the solenoid winding has 1000 turns/m, what is the required current? (0 = 4p 10-7 Tm/A)
a. 5000 A
c. 3980 A
b. 1990 A
d. 1000 A
[Ques. 10] A mass on a spring vibrates in simple harmonic motion at a frequency of 4.0 Hz and amplitude of 8.0 cm. If the mass of the object is 0.25 kg, what is the spring constant?
a. 40 N/m
c. 126 N/m
b. 87 N/m
d. 158 N/m
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