1.A boy vertical throw a ball up in the air, and then catch it. Which at FIG one of the most representative of the position of the ball with respect to time?
Usually you can answer a little faster than the standard five select Done problem classification problem, because you only need to review a set of answer choices to answer a series of questions.
The answer to the question is the position of the ball B with respect to time by the following formula can be expressed as y = -1 / 2 GT2, wherein g is downward, the acceleration of gravity. As we can see, the function y t is an inverted parabola. More intuitive, we know that, over time, the ball throwing in the air will rise, deceleration, stop, and then decreased.
2. In a closed container of gas is steadily heated over a period of time. The following statement is true of this process?
(A) the average kinetic energy of the gas molecules decreases
(B) an increase in the quality of the container
(C) on the gas pressure exerted by the increase of the container on the wall
(D) changing the gas into a liquid phase
(E) the gas is reduced specific heat
The answer to this question is C. The key is to remember that the ideal gas law: PV = NRT.
According to this formula, the increase in temperature accompanied by an increase in pressure. A is wrong because the average kinetic energy of the gas molecules corresponding to their temperature, if the temperature increases, so the average kinetic energy of molecules. B is wrong, because we are dealing with a closed container: quality can not increase or decrease. D is an error, because the gas must be cooled instead of heated, becomes a liquid phase. Finally, E is wrong, a coonstant, because the specific heat of any substance is not subject to change. We will touch on this in Chapter 9: Thermal Physics.