Algodoo

You shouldnt use sim.gravity to change objects gravity direction. Instead, change their poststep to apply artificial accelleration to them (I am using eval for inserting values):
eval("
e.other.poststep = (e)=>{
vel = vel + [0,sim.gravitystrength]/sim.frequency + [Math.cos("+GRAVITYANGLE+"),Math.sin("+GRAVITYANGLE+")]*sim.gravitystrength/sim.frequency
}
")
Replace Gravityangle as the angle of the box with the arrow(you may need to adjust it afterwards) and there you go. every object that collides with the box will have its poststep overwritten to fall in that specific direction until it collides again.