Well, to put this in perspective, meteors that enter the Earth's atmosphere are traveling dozens of thousands of miles per hour relative to us.
And it doesn't really matter how "sturdy" a material is because that can mean different thing. You can have a very hard metal with low heat capacity that will ablate and evaporate due to heat very quickly or a relatively brittle ceramic object of similar weight and shape for which the heat of atmospheric entry isn't an issue. (It might break up due to other issues, though).
Plus, when an object enters a dense fluid medium, it slows down dramatically because the viscosity of a fluid is inversely proportional to its size, which means larger objects retain more of it's velocity and kinetic energy versus a smaller object when it hits the atmosphere. An object the size of a projectile, let's say the size of a railgun/artillery projectile will lose most of it's velocity and speed after it hits the atmosphere.
Imagine the a swimming pool is air and the air above it is vacuum. When you shoot a bullet into a swimming pool from above it, it slows down within a feet or two after it hits the water. In the same way, a railgun projectile isn't really capable of keeping it's kinetic energy after it hits a planetary atmosphere.
Not that it would in the first place, because again, the Earth would be a pinprick in the vastness of space.