A spear is thrown by you at a very high speed. As it passes, you measure its length at 1?2 its normal length. From this you conclude that the moving spear's mass must be

A. one-half its rest mass.
B. twice its rest mass.
C. four times its rest mass.
D. None of these choices are correct.


B. twice its rest mass.

Physics & Space Science

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What is the energy of a photon that has the same wavelength as a 11.4-eV electron? (h = 6.63 × 10^?34 J?s, me = 9.11 × 10^–31 kg, 1 eV = 1.6 × 10^–19 J)

a. 1140 eV b. 32 eV c. 103 eV d. 3420 eV e. 1030 eV

Physics & Space Science

A flux of 4.0 × 10-5 T ? m2 is maintained through a coil of area 7.5 cm2 for 0.50 s. What emf is induced in this coil during this time by this flux?

A) 8.0 × 10-5 V B) 4.0 × 10-5 V C) 3.0 × 10-5 V D) 2.0 × 10-5 V E) No emf is induced in this coil.

Physics & Space Science

Why do white dwarf supernovae all have approximately the same maximum luminosity?

What will be an ideal response?

Physics & Space Science

____ have elongated nuclei with spiral structure extending from the ends of the elongations. The Milky Way is a member of this class of galaxy

a. Spiral galaxies b. Barred spiral galaxies c. Elliptical galaxies d. Irregular galaxies e. S0 galaxies

Physics & Space Science