Where is the Sun located relative to a planet's orbit about it?
a. at the center of the orbit, which is a circle
b. at the center of the orbit, which is an ellipse
c. at one focus of the ellipse which forms the orbit
d. none of the above
c
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In Figure 7.4, the time for the fraction of residual strain in iron to drop to 0.6 at 400°C is 137 minutes, and at 450°C it is 15 minutes.
(a) Calculate the activation enthalpy for the recovery of cold work in iron. (b) Comment on the magnitude of the activation enthalpy for recovery in comparison to the activation enthalpy for vacancy diffusion in iron, and justify your result.
Suppose you are aboard a rocket that is orbiting Earth in the low, circular orbit shown. If you want to escape from Earth and head to the Moon or Mars along the "escape" path shown, what do you need to do?
A) Fire the rocket engine in your direction of travel, so that you gain speed. B) The only way to end up on the "escape" path is to first return to Earth, then launch your rocket with escape velocity. C) Turn the rocket around, and fire the engine so that you lose speed. D) Throw some excess supplies overboard, so that your rocket becomes less massive.
A fission reaction in which more neutrons are given off than are needed to initiate the reaction is called
A) a critical reaction. B) a chain reaction. C) a fusion reaction. D) a neutron catastrophe. E) a chemical reaction.
A ball with a diameter of 20.00 cm is placed in water with 75% of its volume out of the water. The buoyant force of the water on the ball is
A. 16.67 N. B. 14.75 N. C. 13.60 N. D. 12.56 N. E. 10.26 N.