甲、乙两物体沿同一直线运动的vt图象如图所示，则下列说法正确的是（ ）
A．在t＝2 s时，甲、乙两物体的速度不同，位移相同
B．在t＝2 s时，甲、乙两物体的速度相同，位移不同
C．在t＝4 s时，甲、乙两物体的速度相同，位移不同
D．在t＝4 s时，甲、乙两物体的速度不同，位移相同
答案：B
题目分析：在t＝2 s时，两图线相交，甲、乙两物体的速度相同，速度时间图像中图线所围成的面积表示位移大小，可知在t=2s时刻位移不同，A错；B对；在t＝4 s时，甲、乙两物体的速度不同，但面积相同，及位移相同
点评：在应用运动图像求解问题时首先要注意运动图像的类型，理解坐标、斜率、面积所表示的物理意义
| Awarded the Nobel Prize for physics in 1918, German physicist Max Planck is best remembered as the originator of the quantum theory. His work helped usher in a new era in theoretical physics and revolutionized the scientific community’s understanding of atomic and subatomic processes. Planck introduced an idea that led to the quantum theory, which became the foundation of twentieth century physics. In December 1900, Planck worked out an equation that described the distribution of radiation accurately over the range of low to high frequencies. He had developed a theory which depended on a model of matter that seemed very strange at the time. The model required the emission of electromagnetic radiation in small chunks or particles. These particles were later called quantums. The energy associated with each quantum is measured by multiplying the frequency of the radiation, v, by a universal constant, h. Thus, energy, or E, equals hv. The constant, h, is known as Planck’s constant. It is now recognized as one of the fundamental constants of the world. Planck announced his findings in 1900, but it was years before the full consequences of his revolutionary quantum theory were recognized. Throughout his life, Planck made significant contributions to optics, thermodynamics and statistical mechanics, physical chemistry, among other fields. |
"An idea" as used in Line 5, refers to ______.
A．a model of matter
B．emission of electromagnetic radiation
C．quantums
D．the equation that described the distribution of radiation accurately over the range of low to high frequencies