I pull my child in a sled over the snow. The rope makes an angle with the horizontal so that the pulling force has a horizontal component of 16 N and a vertical component in the upwards direction 25 N . The combined weight of the child and sled is 84 N . I'm getting tired and so the sled is slowing at a constant rate of 0.80 m/s each second. Calculate the magnitude of the frictional force between the sled and the snow.