Dynamics (physics 30s)

what is is dynamics

the study of motion with regard to the causes of motion

it is more concerned with WHY is moves, rather than how

What are newtons 3 laws

law of inertia

law of acceleration (momentum)

law of action/reaction

Law of inertia

every body will continue in its same state of motion (rest or uniform straight line motion) unless acted upon by a non zero net of forces

Law of acceleration (momentum)

the acceleration of an object is directly proportional to the force applied to it, but inversely proportional to the objects mass.

(the greater the force, the greater the acceleration)

Law of action/reaction

For every action, there is an equal but opposite reaction

weight

the force an object excerts on a surface due to gravity and its mass

what is friction

a force due to 2 surfaces in contact with one another sliding against each other

it is caused by microscopic imperfections on the surface

friction is always opposite to the force applied

example of the law of inertia

when you are in a bus you are traveling at the same speed as the bus. When the bus breaks, you jerk forward because the breaks act on the vehicle as an external force but you body continues to move at the same speed due to the law of inertia

example of the law of momentum

If you push a box, then push it with double the amount of force, it will go further. When you increase the mass of the box, it will travel less distance because of the law of acceleration

Examole of the law of action/ reaction

when you swim, you push your arms forward in order to go forward, in order to go forward, the water excerts an equal but opposite force back on you