Addition by 1. Components: Find the magnitude and direction of the resultant of the three force vectors, ,, and , shown in the figure. These vectors have the following magnitudes: A = 5.0 lb, B = 7.9 lb, and C = 8.0 lb. Express the direction of the resultant by specifying the angle it makes with the +x-axis, with counterclockwise angles taken to be positive.

style="vertical-align: 0.0px;" height="307" width="314" />

Fill in the blank(s) with the appropriate word(s).

---

1.6 lb, 312°

Physics & Space Science

What is the primary determining factor for a rock's melting/crystallization point?

What will be an ideal response?

A block is launched up an incline plane. After going up the plane, it slides back down to its starting position. The coefficient of friction between the block and the plane is 0.3 . The time for the trip up the plane:

a. is the same as the time for the trip down. b. is more than the time for the trip down. c. is less than the time for the trip down. d. cannot be found without knowing the angle of inclination.

Which of the following was not a major advantage of Copernicus's Sun-centered model over the Ptolemaic model?

a. It made significantly better predictions of planetary positions in our sky. b. It offered a more natural explanation for the apparent retrograde motion of planets in our sky. c. It allowed calculation of the orbital periods and distances of the planets.

What is an artificial star?

A) a meteor B) the unseen member of a binary star system C) a satellite orbiting Earth D) a point of light in Earth's atmosphere created by a laser for the purpose of monitoring atmospheric fluctuations E) a possible source of dark matter in the universe