Imagine you throw a tennis ball vertically into the air. At the exact top of its trajectory it is at rest. What is the magnitude of its acceleration at this point? a. 9.8 m/s2.b. -9.8 m/s2.c. 0.d. other(specify).

When you push downward on a book at rest on a table, you feel an upward force. does this force depend on friction? defend your answer.

Because air contracts as it cools, the air pressure inside a freezer is typically lower than on the outside. why do ice cubes inside a freezer tend to shrink over time? a. the ice dissolves oxygen from the air, forming a denser crystalline matrix.b. the ice reacts chemically with carbon dioxide in the air, forming gaseous carbon compounds.c. the ice melts, and then the liquid freezes as ice crystals on the bottom of the freezer.d. the ice sublimes, and then the water vapor deposits as ice crystals on the sides of the freezer.

Write down two additional questions about earth's magnetic field that will make your presentation more informative.