3.4/3.5 Newtons Third Law of Motion + Kinematics

From note 3.4/3.5 with the glossary terms: Third law of motion, Newton’s third law calculations, Tension and Newton’s Laws, Kinematics and Newton’s Laws

Newtons Third law of motion

Each action force has a reaction force that is equal in magnitude and opposite in direction

Newtons Third law calculations

1) First list out your givens and requires.

2) Put down the same first few lines, F = ma, F = sum of all forces.

3) Keep in mind when making the FBD, that the reaction and action forces have to be OPPOSITE in direction, but they are the same in magnitude

4) Access which thing you are trying to find and what variables are needed to find it. Then rearrange your formulas to find such thing

Tension and Newtons Laws

Since rope/string don’t stretch, that means you don’t need to include the mass of string when calculating the acceleration of 2 objects tied together.

Tension is uniform throughout the rope/string and pulls with the same force at both ends.

When calculating acceleration, you ignore tension because its an Internal force

Tension always on the object directed toward the rope/string.

Kinematics and Newtons Laws

The link between kinematics and dynamics is Acceleration

to find, find acceleration either using F=ma or one of the uniform acceleration equations from kinematics.