In physical activities, you are either static or in motion. When performing physical activities, your body functions to balance multiple forces, enhance forces to reduce and overcome resistance, alter direction of applied force, and enhance your range of motion and speed.
Our bodies have certain movements they must do before they can perform the next movement or there could be loss of coordination, balance, center of gravity, and force. Envision a cheerleader getting ready to perform a split jump. Her feet must be off the ground and her body in the air before she can do the split portion of the the split jump.
Using the example of the cheerleader performing the split jump, let's apply the sequencing of biomechanics and Newton's laws to that physical activity.
Newton's Law of Inertia
Newton's Law of Acceleration
Newton's Law of Reaction
Every body or object at rest or in motion will stay in that state unless it is disturbed by an external force that changes its original state. The cheerleader is at rest until she rotates her arms, bends her knees, and uses her body's force to jump into the air. Her direction is straight up.
A force that is applied to an object or body will accelerate that object or body at a magnitude proportional to the force, in the direction of the force, and proportional to the object's mass. The cheerleader is pushing off her feet and using her arms to force her weight straight up. Her weight is the mass of her body.
In short, for every action there is always an equal and opposite reaction. After the cheerleader goes up, she must come back down. Therefore, as soon as the cheerleader leaves the ground, depending on her mass, muscular strength, and the force she used, she will only have so much hang time before her body has the opposite reaction and comes back down to the ground.
Newton's Laws
Which of Newton's laws states that for every action there is an equal and opposite reaction?