A horse whose mass is M gallops at constant speed v up a long hill whose vertical height is h, taking an amount of time t to reach the top. The horse's hooves do not slip on the rocky ground, so the work done by the force of the ground on the hooves is zero (no displacement of the force). When the horse started running, its temperature rose quickly to a point at which from then on, heat transferred from the horse to the air keeps the horse's temperature constant.(a) First consider the horse as the system of interest. In the initial state the horse is already moving at speed v. In the final state the horse is at the top of the hill, still moving at speed v. Write out the energy principle?Esys = W + Q

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.