PROTO bounce [
  exposedField SFFloat accel 0.1
  ]{
  Transform {
  children [
  Transform {
  translation 0 -10 0
  children [
  Shape {
           geometry Box { size 5 0.2 5 }
           appearance Appearance {
                  material DEF GROUND Material {
                          diffuseColor 1  0 0
                          }
                  }
  }
  ]}