Question

Think back to when you were a kid riding in the backseat of the car. Maybe you once had a milkshake in your hand when your mom hit the brakes. You were secured by your seat belt, but you jer-ked forward and the milkshake splashed all over the front seat…and your mom. That situation probably never happened to you. But think about something that has happened to you physically—a fall, a jump, an accident, or something you may have done hundreds of times in your favorite sport. Analyze the action and describe it in terms of Newton’s laws. Identify the initial conditions and the forces involved. If the action is a sequence of events, analyze it step by step. The more complex the sequence of events, the better!

Answer 1

In Newton’s first law, an object at rest remains at rest until an external force isapplied. When I play soccer, the soccer ball will be at rest on the field (the initial condition) andremain in that spot on the field until I kick it (my muscles applying an external force to the ball).According to Newton’s second law, force = mass x acceleration (F=ma). When I kick the resting soccer ball, which has a given mass, it will accelerate in the direction that I kick it. From the equation, acceleration = force divided by mass. Therefore, since the mass of the soccer ball is fixed, the stronger my leg is and the more force I can apply to the ball, the faster it willaccelerate.According to Newton’s first law, an object in motion remains in motion until an external force isapplied. After I kick the soccer ball, it will continue in motion in the direction that I kicked it,but its acceleration will gradually slow down due to the external forces of friction from the airand the surface of the field. According to Newton’s third law, for every action there is an equal and opposite reaction.When I kick the soccer ball forward, if I also kick it in an upward direction, such as a thirty-degree angle from the field, it will come down at an angle when it strikes the field. When theball lands and strikes the field, there will be an equal and opposite reaction whereby instead oftraveling downward it will bounce of the surface of the field and will then be travelling upward.

Answer 2

According to Newton’s first law, an object at rest remains at rest until an external force is applied. When i play soccer, the soccer ball will be at rest on the field (the initial condition) and remain in that spot on the field until i kick it (my muscles applying an external force to the ball).