44 g of petrified wood was found in a petrified forest. A sample showed a 14C activity of 100 decays/minute. How long has the tree been dead (in years)? (The half-life of carbon-14 is 5730 years and freshly cut wood contains 6.5 × 10^10 atoms of 14C per gram.)
a. 12300
b. 15600
c. 8500
d. 4700
e. 2400
b
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A physics student is riding on a train traveling north. Having read about inertia, the student performs an experiment with a golf ball. He reaches over the aisle and drops the ball from rest. Instead of hitting the floor directly below the student's hand, it hits to the north, i.e., forward of that position. Which of the following might be the cause for this to happen?
a. The train is moving at constant velocity. c. The train is slowing down. b. The train is speeding up. d. Whatever the cause, it cannot be any of the answers given.
The process of transforming sediment into sedimentary rock is called
a. lithification. b. striation. c. metamorphism. d. hardening.
In the figure, if Q = 30 ?C, q = 5.0 ?C, and d = 30 cm, what is the magnitude of the electrostatic force on q?
a.
15 N
b.
23 N
c.
zero
d.
7.5 N
e.
38 N
For a conductor in electrostatic equilibrium, which of the following statements is NOT true?
A. the electric field inside the conductor is zero B. the charge distributes itself uniformly throughout the conductor C. the electric field at the surface of the conductor is perpendicular to the surface of the conductor D. the greatest concentrations of charge on the surface are in the regions of highest curvature E. more than one of these statements about a conductor in electrostatic equilibrium is false