At Chernobyl, one of the harmful radioactive isotopes was 131I, a beta emitter with a halflife of 8 days. The mass number of the nucleus that remains after this isotope decays is
A) 132. B) 129. C) 131. D) 127. E) 130.
B
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A proton moving with a velocity of 4.0 × 104 m/s enters a magnetic field of 0.20 T. If the angle between the velocity of the proton and the direction of the magnetic field is 60°, what is the magnitude of the force on the proton?
A) 1.8 × 10-15 N B) 0.60 × 10-15 N C) 1.1 × 10-15 N D) 2.2 × 10-15 N E) 3.3 × 10-15 N
The Sun is a(n) ______________
Fill in the blank(s) with correct word
As the disk rolls up the incline in the situation described in the previous problem, the friction force acting on the disk does
A. positive work on the disk. B. negative work on the disk. C. no work on the disk.
The proton contains which of the following combination of quarks?
a. two up quarks and one down quark b. one up quark and two down quarks c. one top quark and two bottom quarks d. two top quarks and one bottom quark