The acceleration direction doesn't matter if we want to determine what would happen to a person crashing into a vehicle while they are wrapped in a bubble. It doesn't matter how they bounce when estimating the potential injury to a person's body. It is important to know the acceleration of bounces. The total acceleration is what we need to know. We call it the magnitude of a vector.
The acceleration's x and y components are perpendicular, so they form a right triangle. The hypotenuse is the magnitude. This means I can add the components together and square the root to get the magnitude of acceleration.
Illustration: Rhett Allain
To show you are only using the magnitude of a vector, it is common to place "absolute values" lines around a vector. There is one thing you should remember: Guy's acceleration can be calculated in meters per second. We refer to this as m/s2. It's common to speak of the acceleration of people in terms of g's, where 1 g equals 9.8 m/s2. Guy's acceleration on impact is 25 g.
Already intuitively know the value of 1g. This is because you interact with the Earth's gravitational field every day. (Unless, of course, you're not on Earth. In which case it's fine. Yes, the force you feel when you sit on the couch is 1g. This force is the same force you feel while you walk around town or eat ice cream. You only feel 1 g as long as you don't accelerate.
What is gravity and how does it affect acceleration? This is complicated and rooted within Einstein's Equivalence Principle. However, it basically means that 25 g acceleration would be equivalent to being seated with a force equal 25 times your body weight. Oof.
NASA and other organizations have determined the maximum acceleration that a person can withstand. They call it g force tolerance. It is not one number. It depends on how fast the acceleration increases, how long it takes, how the person is oriented during impact and what the maximum tolerance is.
How about Guy's acceleration of 25 g? Guy could be in serious trouble if the bouncing impact lasts for less than 0.1 seconds. Guy could be seriously or even severely injured if this bounced impact lasts for less than 0.1 seconds.
