Physics Unit 2 - Newton's Laws

Force

An interaction that will change the motion of an object (if unopposed)

The only thing that can cause an object to accelerate is an…

…unbalanced force

Applied force

push/pull

Gravitational force

F_grav, force exerted due to Earth’s mass

Electromagnetic force

F_em, Force between protons and electrons

Frictional force

F_fric, Friction. 2 surfaces sliding against each other, opposes direction of motion

Normal force

F_norm, being supported by an object. Acts against weight

Air Resistance

F_air/F_drag, force from object in air

Spring force

F_spring, force exerted on or by stretched or compressed spring

Tension force

F_ten, rope when tight

Newton’s First Law/Law of Inertia

Unless a net external force, object will stay in motion/rest.

Objects with more interia…

…are more resistant to change.

Mass

Measures the amount of particles that makes you up. Measured in kg or g. UNIVERSAL and independent of location.

Weight

Refers to the amount of gravitational force that acts up on an object. F_grav, = W. Expressed in Newtons. LOCATION DEPENDENT.

Force Diagrams

Represent force vectors by arrows that have a magnitude and direction

If all forces are balanced…

All forces cancel out. a = 0. An object at rest will stay at rest, an object moving will stay moving with a constant velocity

Unbalanced forces

A force that implies acceleration. Net force F_net. Sum of all the forces

Newton’s Second Law

In a scenario where an object DOES have acceleration. Acceleration is directly proportional to net force, acceleration is inversely proportional to mass.a ∝ F_net, a ∝ 1/m

a = F_net

Also F_net = ma