Describe the Ptolemaic model of the solar system. How did Ptolemy account for the apparent retrograde motion of the planets?
What will be an ideal response?
Although Ptolemy's model was an Earth-centered model of the solar system, it was sufficiently accurate to remain in use for 1,500 years. His model used the ancient idea that all motions in the heavens must be perfect circles. Therefore, the planets moved on circles that orbited on larger circles around Earth. This "circle upon circle" motion accounted for the apparent retrograde motion of the planets. Ptolemy carefully selected sizes for the circles to reproduce the motions seen in the sky. He also placed Earth slightly off-center to improve model predictions even more.
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In what type of meteorites are Widmanstätten patterns found?
a. stony b. iron c. stony-iron d. carbonaceous e. centaur
Two objects of equal mass hit a wall with the same velocity. They both rebound with the same velocity. Both objects experience the same momentum change but one experiences twice the force as the other. Which of the following statements is true?
A. the contact time between the object and the wall of one is twice the contact time of the other B. the contact time between the object and the wall of one is equal to the contact time of the other C. the contact time between the object and the wall of one is one-half the contact time of the other D. the change in the kinetic energy is the same for the two objects E. the contact time between the object and the wall of one is 1/3 the contact time of the other
An electron is released form rest in a region of space where a uniform electric field is present. Joanna claims that its kinetic and potential energies both increase as it moves from its initial position to its final position. Sonya claims that they both decrease. Which one, if either, is correct?
a. Joanna, because the electron moves opposite to the direction of the field. b. Sonya, because the electron moves opposite to the direction of the field. c. Joanna, because the electron moves in the direction of the field. d. Sonya, because the electron moves in the direction of the field. e. Neither, because the kinetic energy increases while the electron moves to a point at a higher potential.
What is the difference between forced and free convection?
What will be an ideal response?