A runner generates 1260 W of thermal energy. If this heat has to be removed only by evaporation, how much water does this runner lose in 15 minutes of running? The latent heat of vaporization of water is 22.6 × 105 J/kg
A) 40 g B) 35 g C) 350 g D) 500 g E) 50 g
D
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All of the following statements are true. Which one explains the reason why there is not a solar eclipse at every new moon?
A) The nodes of the Moon's orbit precess with an approximately 18-year period. B) The orbital plane of the Moon is tilted by about 5° to the ecliptic plane. C) The Moon rotates synchronously with its orbit around Earth. D) The Moon's orbital period is slightly shorter than the time it takes for a cycle of phases. E) The Moon's orbital distance varies as it orbits around Earth.
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 magnetic force on the proton? (e = 1.60 × 10-19 C) 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
A flywheel with a moment of inertia 6.00 × 106 kg?m2 is spinning with an angular speed of 120 rev/s about a vertical axis while it sits at the north pole. The disk is turning counterclockwise when viewed from above
The disk is brought to a rest. Treat the earth as a uniform sphere with a mass 5.976 × 1024 kg and a radius 6.374 × 106 m. (a) What will be the magnitude of the change in angular momentum of the earth? (b) What will be the change in length of a day on Earth?
Suppose the ends of a 30-m long steel beam are rigidly clamped at 0°C to prevent expansion. The beam has a cross-sectional area of 30 cm2 . What force against the clamps does the beam exert when it is heated to 40°C? (aSteel = 1.1 × 10^-5/°C, Ysteel = 20 × 10^10 N/m2)