Define Newton's Third Law.
For every action, there is an equal and opposite reaction.
Define 'action-reaction pair'.
A pair of forces equal in magnitude, opposite in direction, acting on different objects.
What is an internal force?
Forces between objects within a system.
What is an external force?
Forces exerted on a system by objects outside the system.
Define 'center of mass (COM)'.
The point where all the system's mass can be considered concentrated.
What is tension?
The force transmitted along the length of a string, cable, or similar object.
Define an 'ideal string'.
A string with negligible mass that does not stretch.
Define an 'ideal pulley'.
A pulley with negligible mass and no friction.
What is the effect of an external force on a system?
It changes the motion of the system's center of mass.
What is the effect of the weight of a real string on the tension?
The tension varies along the length of the string, usually being maximum at the top.
What is the effect of pushing on a wall?
The wall pushes back on you with an equal and opposite force.
What is the effect of internal forces acting within a system?
They cancel each other out and do not affect the motion of the system's center of mass.
What is the effect of using multiple ideal pulleys in a block and tackle system?
They multiply the applied force, making it easier to lift heavy loads.
Define Newton's Third Law.
For every action, there is an equal and opposite reaction.
What is an internal force?
A force between objects within a system.
What is an external force?
A force between an object in the system and something outside the system.
Define tension.
The pulling force transmitted through a string, cable, or similar object when it's pulled tight.
What is an ideal pulley?
A simple machine that changes the direction of a tension force.
