During a positron emission tomography (PET) scan of the brain,
A) an external positron beam is sent through the patient's brain and detected as it leaves the patient.
B) matter and antimatter annihilate within the brain to create positrons that are detected as they leave the patient.
C) radioactive fluorine creates positrons within the brain that are detected as they leave the patient.
D) positrons and electrons annihilate within the brain to create gamma photons that are detected as they leave the patient.
E) highly sensitive detectors measure the positrons that are naturally emitted by the human body.
D
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Two bowling balls with different masses are dropped from the same height. How do their accelerations compare?
A) The heavier bowling ball accelerates faster. B) They both fall with the same acceleration. C) The lighter bowling ball accelerates faster.
The position of a mass that is oscillating on a spring is given by x = (17.4 cm) cos[(5.46 s-1)t]. What is the angular frequency for this motion?
A) 0.183 rad/s B) 5.46 rad/s C) 2.34 rad/s D) 17.4 rad/s E) 0.869 rad/s
The redshifts of the galaxies imply that the Universe is expanding and that we are at the center
Indicate whether the statement is true or false
How could the Universe be accelerating, despite the gravitational pull of all the matter in it?
A.) There's no friction in space. B.) There could be less dark matter than we think. C.) There could be a new force or property of space that affects the Universe on its largest scales. D.) Our laws of nature are incorrect. E.) Probably B and C.