Forces 01

Force

A push or a pull; an interaction between two objects

Is force a vector quantity?

Yes; it has a magnitude and a direction

What is a Net Force?

The Net Force is the vector sum of all the individual forces acting on an object, determining the object's acceleration and overall motion.

Kinematics

The description of how an object moves including its position, velocity, and acceleration over time.

Dynamics

Relating force to motion.

Gravitational force (aka, weight)

Gravity acts on all objects, pulling them toward the center of the Earth with a force proportional to their mass.

Gravitational force (equation):

F_g = mg

Which direction does the gravitational force vector always point?

Vertically downward, towards the center of the Earth.

Mass

The quantity of matter in an object.

Weight

The force exerted on an object due to gravity (calculated as mass times gravity).

An object at rest has a _ net force

0

Normal force

The force that a surface exerts on an object (remember: only present if there is a surface present).

Normal force is always _ to the surface.

perpendicular

Normal force (symbol)

F_N or N

Frictional force

The force that opposes the relative motion of two surfaces in contact (remember: only present if there is a surface present).

Frictional force is always _ to a surface.

parallel

Frictional force (symbol)

f

Tension force

A force that is transmitted through a string, rope, or cable when it is pulled tight by forces, exerting a contact force

Tension force (symbol)

T or F_T

Spring force

The force is exerted by a compressed or stretched spring; the spring always returns to its original state after being compressed/stretched.

Newton’s First Law of Motion

An object at rest stays at rest, and an object in motion remains in motion unless acted upon by a net external force.

Newton’s Second Law of Motion

The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass, giving the formula $F = ma$.

Newton’s Third Law of Motion

For every action, there is an equal and opposite reaction.