Physics are weird. They basically run the universe. Some only happen when there's gravity present, some happen in space. Let's explain a couple scenarios.

Getting killed by a high impact on water
As (almost) everyone should know, when you fall onto solid ground at a high velocity, you die not from the impact, but from the sudden stop. Water has the same effect if you're high enough. Most people think that if you have the choice between hitting water or landing from a high altitude, the water would be the better option, but not necessarily. A solid is essentially atoms that are fixed in the same place. They're hardly active. The atoms of a liquid, however, move more than a solid. They freely move at a tame pace and can cross over one another. But why does this have the same effect as hitting a solid from a high altitude? Well, say you hit the water normally with a flat hand. The water will sting your hand. This is because the water molecules don't have enough time to move out of the way. When falling, this is produced on a larger scale, but is essentially the same. It's like hitting a solid because, like a solid, when you hit it at first, the molecules are stationary.

Now for a quick closing lesson

Ionizing Radiation
Radiation comes in many forms. Electromagnetic, light, and much more. Radiation is essentially waves or particles, But ionizing radiation is different. Electromagnetic waves are essentially radio waves and X-Rays. They can harm you in large quantities but not as bad as ionizing radiation. Ionizing radiation essentially rips the electrons away from an atoms nucleus, thus, making said atom an ion. This hurts us when large molecules (i.e. Nucleic acid) get ionized, or excited and change the molecular make up of said molecules which then affect the function and metabolism of the molecules. This can happen throughout the body. You can't immediately feel, smell, taste, or sense in any way, ionizing radiation. Over time however, if you're exposed to ionizing radiation for too long, then this could be severely harmful or even lethal. Every day you're exposed to non-lethal or harmful levels of radiation. Ways you receive these doses are through cosmic sources, metals, mining, and even eating bananas (potassium.) Some jobs have a bit of a higher exposure of radiation than most jobs. These jobs consist of pilots, miners, and weapons testers. Ionizing radiation is measured in Sieverts. On average, most people get about 2.4 milisieverts of radiation per year which is the equivalent to eating 24,000 bananas with bananas giving off 0.1 microsievert or one tenth of a millionth of a sievert. Being exposed to just one sievert is enough to cause complications and the lethal level of radiation is 8 sieverts.

Well, now you know that much more about physics and stuff. Hope you use this knowledge when near radioactive waste or when you forget a parachute. Byeeeee.