> When you take a sharp turn in an automobile, and your body suddenly leans to oneside, which law in physics is at play?And the answer: inertia. Photo credit: Volker Möhrke / Getty Images.The English mathematician andphysicist Sir Isaac Newton identified three laws of motion, the first of whichinvolves inertia. According to Britannica, "Newton’s first law states that if abody is at rest or moving at a constant speed in a straight line, it will remainat rest or keep moving in a straight line at constant speed, unless it is actedupon by a force."Interestingly, Newton wasn't the first to postulate a theory of inertia. Hisfirst law actually grows out of ideas put forth by Galileo Galilei, a famousastronomer who originally sought to make sense of the horizontal motion of theEarth. For Galileo, the theory of inertia contained the key to one unanswerablequestion (thus far): how can the Earth spin constantly without us feeling it?Ultimately, his question was answered by this postulate. Since we are in motiontogether with Earth and our natural tendency is to retain that motion, Earthappears to us to be at rest.Aside from the law of inertia, two other theories ground Newton's laws ofmotion. The second law is that of force, or velocity. Newton theorized that theamount of force placed upon an object before movement is equal to the time rateof change of the momentum of that object. That's all to say, however much youput in (ie, the amount of power you use to throw a ball), will be equal to themomentum it garners (ie how far the ball goes, and in what direction). Velocity,as he states, has both magnitude and direction. Thus he created an equation: F =ma. This equation applies to bodies who's mass (m) is constant, while the F, forforce, and a, for acceleration, both contain magnitude and direction. Thisequation went on to become one of the most central notions of the study ofphysics. The third and final law is that of action and reaction. Newton’s third lawstates that when two bodies interact, they apply forces to one another that areequal in magnitude and opposite in direction. For example, a ball sitting on atable is applying downward force equal to the weight of the table. According tothe third law, the table applies an equal and opposite force to the ball.Learn more about Newton's Laws of Motion here[https://www1.grc.nasa.gov/beginners-guide-to-aeronautics/newtons-laws-of-motion/].