A 0.30-kg rock is swung in a circular path and in a vertical plane on a 0.25-m-length string. At the top of the path, the angular speed is 12.0 rad/s. What is the tension in the string at that point?
a. 7.9 N
b. 16 N
c. 18 N
d. 83 N
a
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The units of impulse are equivalent to:
a. those of energy. b. N/m. c. kg/m/s. d. those of force.
At a particular point and instant, the magnetic field component of an electromagnetic wave is 15.0 ?T. What is the magnetic energy density of this wave at that point and instant?
(c = 3.00 × 108 m/s, ?0 = 4? × 10-7 T ? m/A, ?0 = 8.85 × 10-12 C2/N ? m2 ) A) 4.47 × 10-4 J/m3 B) 9.72 × 10-5 J/m3 C) 2.26 × 10-4 J/m3 D) 8.95 × 10-5 J/m3 E) 1.79 × 10-4 J/m3
Suppose we have determined the orbital period of a planet around its star. If we also know the mass of the star, then we can use the planet's orbital period and the star's mass to calculate
A) the planet's average orbital distance. B) mass of the planet. C) eccentricity of the planet's orbit. D) radius of the planet.
A typical source of infrared radiation is
A) magnetized particles vibrating in iron and certain other metals. B) charged particles moving within the nucleus. C) electrons moving along a metal antenna. D) thermal vibrations of molecules. E) electrons orbiting the nucleus in atoms.