A roller coaster descends 50.00 m from the top of the ride, to the first low point at the ground level. The roller coaster converts gravitational potential energy to kinetic energy with an efficiency of 60%. What is the velocity of the roller coaster at the first low point?

Aspring is used to stop a 50-kg package which is moving down a 20º incline. the spring has a constant k = 30 kn/m and is held by cables so that it is initially compressed 50 mm. knowing that the velocity of the package is 2 m/s when it is 8 m from the spring and neglecting friction, determine the maximum additional deformation of the spring in bringing the package to rest.