You find a mysterious rock on the ground and determine that 60% of its uranium-235 has been converted into lead-207. What is the most likely origin of the rock, based on its radiometric age?
A) It's older than our solar system, so it must have come from another solar system.
B) It's a meteorite dating back to the formation of the solar system.
C) It's a volcanic rock nearly a billion years old.
D) It was just formed this year during the eruption of a nearby volcano.
C) It's a volcanic rock nearly a billion years old.
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Most of the hydrogen bomb's energy comes from
A) a chemical reaction. B) magic. C) fission. D) fusion. E) radioactive decay.
A 1.5-kg object has a velocity of 
m/s at t = 0. It is accelerated at a constant rate for five seconds after which it has a velocity of 
m/s. What is the magnitude of the resultant force acting on the object during this time interval?
A. 3.8 N B. 3.2 N C. 2.8 N D. 4.3 N E. 4.6 N
A nearsighted person has a far point that is 4.2 m from his eyes. What power contact lenses must he wear to allow him to focus on distant mountains?
A) 0.24 diopters B) -0.36 diopters C) -0.48 diopters D) -0.24 diopters E) 0.48 diopters
A sphere of radius 25 cm is at the bottom of a pool containing fresh water. If the total force on the sphere due to the water is 1025 N, what is the depth of the sphere below the surface? The air pressure outside is 101.5 kPa.
A. 7.6 m B. 5.7 m C. 52.8 m D. 13.2 m E. 2.9 m F. 39.6 m