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force

a push or pull that acts on an object

newton

the force that causes a 1-kilogram mass to accelerate at a rate of 1 meter per second each second

net force

the overall force acting on an object after all forces are combined

friction

a force that opposes the motion of objects that touch as they move past each other

static friction

the friction force that acts on objects that are not moving

rolling friction

the friction force that acts on rolling objects

fluid friction

the friction force that opposes the motion of an object through a fluid

gravity

the force that acts between any two masses

terminal velocity

the constant velocity of a falling object when the force of air resistance equals the force of gravity

projectile motion

the motion of a falling object after it is given an initial forward velocity

inertia

the tendency of an object to resist a change in motion

mass

the amount of matter an object contains

weight

the measure of the force of gravity on an object

momentum

the product of an object's mass and velocity

law of conservation of momentum

the total momentum of a closed system does not change

electromagnetic force

a force associated with charged particles, which has two aspects, electric force and magnetic force

strong nuclear force

a powerful force of attraction that acts only on the neutrons and protons in the nucleus, holding them together

weak nuclear force

a powerful attractive force that acts over a short range

gravitational force

an attractive force that acts between any two masses

centripetal force

a center-directed force that continuously changes the direction of an object to make it move in a circle