It takes 6400 years for one gram of radium to decay away to only 1/16—one-sixteenth—of a gram. The half-life of radium is
A) not possible to determine from this information.
B) 1600 years.
C) 400 years.
D) 3200 years.
E) 800 years.
B
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A plane has an eastward heading at a speed of 156 m/s (relative to the air). A 20.0 m/s wind is blowing southward while the plane is flying. The velocity of the plane relative to the ground is
A) 157 m/s at an angle 7.31° south of east. B) 157 m/s at an angle 7.31° east of south. C) 155 m/s at an angle 7.36° south of east. D) 155 m/s at an angle 7.36° east of south. E) 157 m/s at an angle 7.36° south of east.
If Newton's law of universal gravitation turned out to be Gm1m2/r rather than Gm1m2/r2, tides on Earth
A. would not happen because the force of gravity from the Moon would be too strong. B. would still occur because each side of the Earth would feel a different gravitational force from the Moon. C. would not occur because gravity would then be a repulsive force. D. would not occur because the Sun would cancel out the Moon's gravity.
Electric generating plants are usually rated in "megawatts". This is a unit of
A) force. B) power. C) energy. D) both energy and work. E) work.
A body is oscillating up and down at the end of a spring. Let's consider when the body is at the top of its up-and-down motion.The displacement vector from the equilibrium position
a. is zero. b. has its largest magnitude. c. points up. d. points down.