Grade 11 Physics Concepts: First Law
First Law: Inertia!!
To start this blog post off is a definition of the first law, the concept of inertia: “If the external net force on an object is zero, the object will remain at rest or continue to move at a constant velocity.” This is because an object’s tendency to stay in motion, or stay at rest and continue forward at a constant speed. This means that an object at rest will stay at rest unless a net force acts on it. Objects with more mass have more inertia than objects with a smaller mass.
When a car is in motion and the passenger inside is strapped into the car, then it is connected with it and will decelerate and accelerate with the car. If the passenger is not wearing a seat belt, they would not share the same state of motion as the car anymore and would fly out of their seat at the moment of impact with a wall or another vehicle, as they would be maintaining their own state of motion, and not the car’s.
The following is a video clip of an originally 22 minute long video about the physics of car crashes. It has a slight bit of an 80-90's early 2000's science show feeling, but it is informative, slightly tacky and enjoyable at the same time. It may appear that I have an endearment to such shows, probably due to the influence of Bill Nye.... haha. (4minutes 20seconds)
Small summary:
The basic laws of physics can make a huge difference between a fatal and light car accident. The insurance institute for highway safety's vehicle research centre has research engineers test crash performance for vehicles by running tests on numerous cars. It is a practical application laboratory that tests for car crashes and analyze these crashes so they can show the laws that govern the physics of car crashes. Inertia causes objects at rest to want to remain at rest, which shows why a crash dummy falls off a car once it accelerates and moves forward. Another example is of a car and the passenger, moving at the same speed. If the car is to stop abruptly, the passenger inside would continue moving forward and crash into the dashboard of the car. The front of the car crumples, cushioning the crash, however the passenger inside would still slam forward and into the car. A body of motion travels at the same speed, and remains travelling at that speed and direction until they are acted upon by an outside force. Inertia is why seatbelts are important. When wearing a seatbelt, the occupant would travel at the same speed even when the car slows down, which prevents the passenger from crashing into the windshield of the car.
The following is a second video, similar in content with the previous one, but informative and short in its own sense. (2minutes 40seconds)
