The length of a certain wire is doubled and at the same time its radius is reduced by a factor of 2. What is the new resistance of this wire?
A) It is 2 times as large.
B) It is 4 times as large.
C) It is 6 times as large.
D) It it 8 times as large.
E) It is ½ as large.
D
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Which of the following terms describe lenses that are thinner at the center than at the edges? (There could be more than one correct choice.)
A) convex lenses B) diverging lenses C) converging lenses D) concave lenses
Suppose your normal resting heart rate is 60 beats per minute. Now, suppose you board a spaceship that travels away from Earth at 90% of the speed of light. While on the ship, you measure your heart rate. What will it be?
A) It will still be 60 beats per minute. B) It will be 46 beats per minute. C) It will be 74 beats per minute. D) It will be 12 beats per minute.
Radio waves travel
A) always much faster than sound waves. B) in common cases at the same speed as sound waves. C) slower, on average, than sound waves. D) at a speed that depends on frequency.
A sound wave in helium has an intensity of 
The density of helium is 0.179
and the velocity of sound in helium is 965 m/s. The pressure amplitude of the sound wave is
A. 
B. 
C. 
D. 
E. 