To unload the truck, the man pushes the crate down the ramp, which is now angled at 13°, using a force of 503N. What is the acceleration of the crate down the ramp?
It depends on information not available.
What is the mass of the crate?
In what direction is the 503 N force exerted?
Is friction to be considered?
As an example, I will choose information to be added and then give the acceleration:
The mass of the crate is 228 kg. The direction of the applied 503 N force is up the ramp. Ignore friction, the crate is on massless wheels.
The acceleration will be given by Newton's 2nd Law
The net force,
So the net force on the crate is zero. Therefore the acceleration is zero. The man forces the crate to go down the ramp at constant speed because there is a right turn he must make at the bottom of the ramp.
I hope this helps,