Energy, work and power — practice question

A playground slide slopes downward at a fixed angle of $30^\circ$ over 2.5 m. After this, it continues as a horizontal part lying in the same vertical plane as the inclined part. A child of mass 35 kg, modelled as a particle P, begins from rest at the top of the slide and moves directly down the sloping part. She then travels along the horizontal part until she stops (see diagram). As the child moves from the sloping part to the horizontal part, her speed does not change instantaneously. A resistive force acts on the horizontal part of the slide, and the work done against the resistive force on the horizontal part of the slide is 250 J per metre. The sloping part of the slide is smooth.