When water flows through river rapids or over a waterfall, it experiences a decrease in height and thus a decrease in gravitational potential energy. Some of this energy goes into producing noise and eroding rock, but much of the energy goes into heating the water. A river flows over a waterfall of height h = 45 m. Assume all the available gravitational energy is converted into internal energy of the water. There is no change in the kinetic energy, because the flow speed of the river is the same above and below the waterfall. Part (a) Enter an expression for the change in temperature of the water, in terms of the height of the waterfall, h, the specific heat of water, c, and the acceleration due to gravity, g. Expression: AT Select from the variables below to write your expression. Note that all variables may not be required. B, 7, , b, c, d, e, g, h, j, k, m, n, P, S
Part (b) Calculate the change in temperature, in degrees Celsius, of the river water in this problem. The specific heat of water is 4.19x10 J/(kg.°C). Numeric : A numeric value is expected and not an expression. AT

Part f - example: finding two forces (part i) two dimensional dynamics often involves solving for two unknown quantities in two separate equations describing the total force. the block in (figure 1) has a mass m=10kg and is being pulled by a force f on a table with coefficient of static friction îľs=0.3. four forces act on it: the applied force f (directed î¸=30â above the horizontal). the force of gravity fg=mg (directly down, where g=9.8m/s2). the normal force n (directly up). the force of static friction fs (directly left, opposing any potential motion). if we want to find the size of the force necessary to just barely overcome static friction (in which case fs=îľsn), we use the condition that the sum of the forces in both directions must be 0. using some basic trigonometry, we can write this condition out for the forces in both the horizontal and vertical directions, respectively, as: fcosî¸â’îľsn=0 fsinî¸+nâ’mg=0 in order to find the magnitude of force f, we have to solve a system of two equations with both f and the normal force n unknown. use the methods we have learned to find an expression for f in terms of m, g, î¸, and îľs (no n).

Alfred pushes on a heavy box, but cannot move it. the box has a lot of inertia motion friction gravity

Alandscaper is shopping for landscaping materials. she wants to use materials through which water flows easily. which materials should she choose? check all that apply. clay gravel granite rocks with cracks loosely packed soil