A child slides down a snow-covered slope on a sled. At the top of the slope, her mother gives her a push to start her off with a speed of 0. 90 m/s. The frictional force acting on the sled is one-fifth of the combined weight of the child and the sled. If she travels for a distance of 27. 0 m and her speed at the bottom is 4. 25 m/s, calculate the angle that the slope makes with the horizontal.