A roller coaster reaches the top of the steepest hill with a speed of 7.0 km/h . It then descends the hill, which is at an average angle of 44 ∘ and is 30.0 m long.

Question

A roller coaster reaches the top of the steepest hill with a speed of 7.0 km/h . It then descends the hill, which is at an average angle of 44 ∘ and is 30.0 m long.
Estimate its speed when it reaches the bottom. Assume μk=0.18.