Any Strategies??

Question

A pitcher throws a .142kg baseball at 47.2 m/s. As it travels a distance of 19.4m, the ball slows to 42.5 m/s because of air resistance. Find the change in temperature of the air through which the ball passes. The following assumptions may be made: molar specific heat of air is (7R/2), molar mass of air is 28.9 g/mole, and the cover insulates the interior of the ball so the ball's temperature does not change. The temperature change happens in a cylinder of 19.4m length and radius of 3.7cm. Air temperature is 20 degrees Celcius.

Answer 1

Your teacher is wicked! I like him (or her)! You're going to need to pull together several things to solve this one.

First, you figure out the energy lost by the baseball. You have the speed at the beginning and at the end and the mass. You can figure out the kinetic energy at the beginning and at the end. Pull out the formula for kinetic energy of an object in translation from classical mechanics for that one. The energy lost by the baseball is assumed to go entirely into heating up the surrounding air because none of it went into heating up the ball given the insulation.

To figure out what the temperature rise is, first you figure out how much air there is. You can figure out the volume of air in the tube. You have to assume that it is at ambient pressure of 1 atmospheres (or another one if your teacher specifically states another pressure). Since he or she didn't, we assume ambient. You are also going to assume the pressure change due to the presence of the baseball is negligible. Otherwise, you have to subtract out the volume of the baseball from the computation of volume of air in the tube. Since the size of the ball isn't specified, we're going to assume the pressure change is negligible.

Given the volume of air in the tube, the pressure, and the temperature of 20 degrees C, you can figure out the number of moles of air in the tube that has to be heated. Pull out the ideal gas law for that one. From that, you multiply by molar mass to find the mass of air to be heated.

With the amount of energy lost by the ball (which equals energy gained by surrounding air), the mass of air that needs to be heated (and assume it is heated uniformly) and the specific heat of air, you can figure out the temperature rise of that amount of air.

Answer 2

Its said " guy proposes god disposes " that is very genuine , each thing takes position because it own guidelines created by god , yet we imagine we are to blame for that . if issues comes as we needed we get satisfied else we curse god and others . i trust god and destiny . so i comprehend no longer some thing in our hands , yet that doesnt advise you should no longer do ideas , ideas are certainly reliable also ought to too it provides sparkling expertise of what you're doing , so have ideas in the route of life yet not at all assume it would artwork , issues comes there in effortless words , if one ideas fails then try for yet another yet dont get vexation if it fails .