Understanding Newton’s Three Laws of Motion

Which Experiences the Greater Force? The Kicker? The Football? (Trick Question!)

Newton’s Third Law of Motion Remember: For every action there is an equal and opposite reaction. Fa,b = -F b,a The force from object A on object B is exactly equal, but opposite to the force from object B back on object A

Don’t The Action-Reaction Forces Cancel Out? Algebraically the forces do cancel out (Newtons = -Newtons) equal in magnitude and opposite in direction Force is acting on two separate objects! HINT HINT: Each object has a different mass…

Which Experiences the Greater Change in Motion? The Kicker? The Football? (Better Question!) Explain by using Newton’s Three Laws of Motion

Does the Football Player or Football Experience a Greater Change in Motion? (Football) A F= m x A Football experiences a HUGE acceleration but has a SMALLER mass compared to the football player Football experiences positive acceleration (speeding up) (Football Player) M F= M X -a Football player experiences a SMALLER and NEGATIVE acceleration (deceleration of leg) but the player has a LARGER mass than the football Football Player experiences a negative acceleration

Remember Newton’s Second Law of Motion… F=ma F=ma, where F is the net external force, m is the mass, and a is the acceleration The more mass an object has the less likely it would be to change whatever it is doing…and if you push harder you will get a bigger change in motion. In other words… as M increases A will decrease (A is indirectly related to M)

Remember Newton’s First Law of Motion… An object at rest remains at rest, and an object in motion continues in motion with constant velocity. Inertia Inertia- an object’s resistance to acceleration or change in motion In other words…The more M something has the greater its inertia or resistance to change (M is directly related to I )

Which Experiences a Greater Change in Force & Motion? The Bullet? The Gun?

Which Experiences a Greater Change in Motion? The Truck? The butterfly by the Truck?