Một chất điểm bắt đầu chuyển động nhanh dần đều. Nếu trong giây đầu nó đi được 3m thì giây tiếp theo nó sẽ đi được:
A. 6 m B. 9 m C. 12m D. 15 m

Conceptualize notice how this problem differs from our previous discussion of gauss's law. the electric field due to point charges was discussed in the previous section. now we are considering the electric field due to a distribution of charge. we found the field for various distributions of charge in the chapter entitled electric fields by integrating over the distribution. this example demonstrates a difference from our discussions in the previous chapter. in this chapter, we find the electric field using law. categorize because the charge is distributed uniformly throughout the sphere, the charge distribution has spherical symmetry and we can apply gauss's law to find the field. analyze note that the following conditions can be used to determine a suitable gaussian surface. condition (1): the value of the electric field can be argued by symmetry to be constant over the portion of the surface. condition (2): the dot product e â· da can be expressed as a simple algebraic product e da because e and da are parallel.