Polonium-215 alpha decays with a half life of 1.8 ms
(a) How much is left after 1. second?
(b) What is the daughter nucleus?
(a) fraction remaining: N/No = 4.2 × 10-170
(b) Lead-211
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Circular Motion of Charges: Alpha particles, each having a charge of +2e and a mass of 6.64 ×10-27 kg, are accelerated in a uniform 0.50 T magnetic field to a final orbit radius of 0.50 m. The field is perpendicular to the velocity of the particles. What is the kinetic energy of an alpha particle in the final orbit? (1 eV = 1.60 × 10-19 J, e = 1.60 × 10-19 C)
A. 3.0 MeV B. 2.6 MeV C. 3.4 MeV D. 3.9 MeV E. 4.3 MeV
An aluminum cantilever beam of length L 5 0.65 m carries a distributed load, which includes its own weight, of intensity q/2 at A and q at B. The beam cross section has a width of 50 mm and a height of 170 mm. Allowable bending stress is 95 MPa and allowable shear stress is 12 MPa. The permissible value of load inten- sity q is approximately:
(A) 110 kN/m
(B) 122 kN/m
(C) 130 kN/m
(D) 139 kN/m
Power is transmitted at high voltages because the corresponding current in the wires is
A) also high to deliver appreciable power to distant places. B) low so that overheating of the wires is minimized. C) either of these D) neither of these
Who discovered the period-luminosity relationship, and why was it so critical?
What will be an ideal response?