Science Forces, Momentum, and Friction

Momentum

a property of an object that is related to how much force is necessary to change its motion. A vector quantity, as it has velocity which has direction

SI Unit for Momentum

kg x m/s

Formula for Momentum

p = m·v

Law of Conservation of Momentum

—Momentum can be transferred from one object to another

—The momentum of an object will not change (it is conserved) unless its mass, velocity, or both, change

—“In the absence of an external force (gravity, friction), the total momentum before the collision is equal to the total momentum after the collision, or is CONSERVED.”

Elastic Collisions

collisions where the objects bounce off of each other or separate.

Inelastic Collisions

—collisions where the objects stick together and move as one. The mass after the collision is equal to the sum of the masses and there is just one final velocity.

Impulse-Momentum Theorum

the impulse (the time over which a force is applied) acting on an object is equal to the change in momentum of the object (its mass x  the change in velocity)

Impulse Equation

Impulse (force x time) = change in momentum (mass x change in velocity)

Force

A push or pull that one object can exert on another, causing the object to change in position (move/accelerate)

f=ma

Formula for force (force = mass x acceleration)

kg x m/s² (Newton)

SI unit for force

Balanced Force

when equal forces in opposite directions are applied to an object, resulting in no change in motion as they cancel out

Unbalanced Force

When a force is applied to an object and is not balanced by another force, resulting in a change in motion / acceleration

Net Force

The result (sum) of all forces acting on an object

Inertia

-The tendency of an object to resist a change in motion

-A property of matter (mass)

-The greater the mass of an object, the greater its resistance to a change in motion

Newton’s 1st Law of Motion

The tendancy of an object to resist a change in motion unless acted on by an unbalanced force.

Newton’s 2nd Law of Motion

An object will accelerate in the direction of the net force

Law of Universal Gravitation

The attractive force between any two masses that is greater when the objects are closer together and have more mass

Newton’s 3rd Law

Every action has an equal opposite reaction

Friction

The force between two surfaces that are touching one another

Factors Affecting Friction

The objects’ masses and the materials touching each other

Fluid Friction

The friction of an object moving through a fluid

Static Friction

The friction between two surfaces that are not moving past each other - the greatest type of friction due to needing to overcome it to begin motion

Rolling Friction

The friction between a rolling object and the surface it rolls on - the least amount of friction because each point of the wheel does not make contact with the surface it rolls on for long enough for the surfaces to interlock

Centripetal Force

A force directed toward the center of a circle for an object traveling in a circular path