1. A roller coaster reaches the top of the steepest hill with a speed of 6.0 km /h. It then descends

1. A roller coaster reaches the top of the
steepest hill with a speed of 6.0 km /h. It then descends the hill, which is at
an average angle of 45° and is 45.0 m long. What will its speed be when it
reaches the bottom? Assume

2. An 18.0-kg box is released on a 37.0°
incline and accelerates down the incline at 0.220 m /s2. Find the
friction force impeding its motion. How large is the coefficient of friction?