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Motion and Forces Unit Test Vocabulary

Key Concepts:

Terms in this set (33)

Distance
how far an object has moved
Displacement
how far an object has moved AND the direction it has moved
Speed
the distance an object travels per unit of time; the rate at which an object moves
Average Speed
the total distance an object travels divided by the total time
Instantaneous Speed
the rate at which an object is moving at a given instant in time
Velocity
speed in a given direction
Acceleration
the rate at which velocity changes (can be speeding up, slowing down, or changing direction)
Deceleration
negative acceleration, when an object slows down
Slope
the steepness of a line graph; rise over run
Force
a push or a pull
Newton
the SI unit of force
Net Force
the combination of all forces acting on an object
Balanced Forces
when equal forces are acting on an object in opposite directions (net force = 0)
Unbalanced Forces
result in a net force and cause a change in the object's motion
Friction
the force that two surfaces exert on each other when they come in contact
Static Friction
the force of friction that acts on objects that are not moving
Sliding Friction
the force of friction that occurs when two surfaces slide over each other
Rolling Friction
the force of friction that occurs when an object rolls across a surface
Fluid Friction
the force of friction that occurs when a solid object moves through a fluid
Gravity
an attractive force that pulls objects toward each other; affected positively by mass and negatively by distance
Mass
the amount of matter in an object
Weight
the force of gravity acting on an object; varies with the strength of the gravitational field
Air Resistance
a type of fluid friction, occurs as objects move through the air
Terminal Velocity
the greatest velocity a falling object reaches when the force of air resistance cancels out acceleration due to gravity
Projectile
an object that is thrown
Projectile Motion
the curved path that projectiles follow due to horizontal and vertical motion, which are independent of each other
Inertia
the tendency of an object to resist a change in motion
Newton's 1st Law of Motion
an object at rest remains at rest, and an object in motion remains in motion (at constant velocity) until acted upon by an unbalanced force
Newton's 2nd Law of Motion
acceleration depends on the object's mass and on the net force acting on the object
Newton's 3rd Law of Motion
if one object exerts a force on another object, then the second object exerts a force of equal strength in the opposite direction on the first object (for every action there is an equal and opposite reaction)
Momentum
a characteristic of a moving object that is related to the mass and velocity of the object
Law of Conservation of Momentum
in the absence of outside forces, the total momentum of objects that interact does not change
Centripetal Force
any force that causes an object to move in a circular path
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