Water is flowing in a trapezoidal channel at a rate of q = 20 m3/s. the critical depth y for such a channel must satisfy the equation 0=1-(q^2 b)/(ga_c^3 ) where g is gravity, ac is the cross-sectional area, and b is the width of the channel at the surface. for this case, the width and the cross-sectional area can be related to depth y by b = 3 + y and ac = 3y + 1/2y2. use initial guesses for the location of the root of a=0.5 and b= 2.5. the error on the solution should not exceed 1%.

Multiple choice. choose the one alternative that best completes the statement or answers the question. 1) if the force on an object is in the negative direction, the work it does on the object must be 1) a) negative. b) positive. c) the work could be either positive or negative, depending on the direction the object moves. 2) a truck has four times the mass of a car and is moving with twice the speed of the car. if kt and kc refer to the kinetic energies of truck and car respectively, it is correct to say that 2) a) kt = 16kc . b) kt = 1 2 kc. c) kt = kc . d) kt = 2kc . e) kt = 4kc . 3) you and your friend, who weighs the same as you, want to go to the top of the eiffel tower. your friend takes the elevator straight up. you decide to walk up the spiral stairway, taking longer to do so. compare the gravitational