A long straight wire (diameter = 2.0 mm) carries a current of 40 A. What is the magnitude of the magnetic field 1.5 mm from the axis of the wire?
a. 3.0 mT
b. 12 mT
c. 5.3 mT
d. 7.4 mT
e. 8.0 mT
c
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Two projectiles are launched at 100 m/s, the angle of elevation for the first being 30° and for the second 60°. Which of the following statements is false?
a. Both projectiles have the same acceleration while in flight. b. The second projectile has the lower speed at maximum altitude. c. Both projectiles have the same range. d. All of the above statements are true.
A hydraulic lift raises a 2000-kg automobile when a 500-N force is applied to the smaller piston. If the smaller piston has an area of 10 cm2, what is the cross-sectional area of the larger piston?
A. 40 cm2 B. 80 cm2 C. 196 cm2 D. 392 cm2 E. 160 cm2
Two very small spherical metal objects, each with 1 Coulomb of charge, are brought together in a vacuum so that the separation distance between their centers is 1 mm. What is the force of repulsion between the two objects? (Coulomb's constant is k=9.0 × 109 N.m2/C2.)
A. 9 × 1014 N B. 9 × 1015 N C. 9 × 1012 N D. 9 × 1013 N
A metal bar is used to conduct heat. When the temperature at one end is 100°C and at the other is 20°C, heat is transferred at a rate of 32 J/s. The bar is then stretched uniformly to twice its original length. If again it has ends at 100°C and 20°C, at what rate will heat be transferred between it ends?
a. 4 J/s c. 16 J/s b. 8 J/s d. 32 J/s