Suppose an object is set sliding with a speed less than escape velocity on an infinite frictionless plane in contact with the surface of the Earth,...

Suppose an object is set sliding with a speed less than escape velocity on an infinite frictionless plane in contact with the surface of the Earth, as shown. Describe its motion. (Will it slide forever at a constant velocity? Will it slide to a stop? In what way will its energy changes be similar to that of a pendulum?)