I’d say you need it not just because it’s a default assumption, but because it’s also an inaccurate assumption. Sort of like how you specify that an inclined plane is frictionless and in a vacuum, but you don’t mention that it’s under the force of gravity, or that it will force away any object that would otherwise pass through it.
I’d say you need it not just because it’s a default assumption, but because it’s also an inaccurate assumption. Sort of like how you specify that an inclined plane is frictionless and in a vacuum, but you don’t mention that it’s under the force of gravity, or that it will force away any object that would otherwise pass through it.