50 terms

# Physics, Chapter 12

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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 (1m/s2)
net force
the overall force acting on an object, after all the forces are combined
sliding friction
a force that opposes the direction of motion of an object as it slides over a surface
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
opposes the motion of an object moving through the air
air resistance
fluid friction acting on an object moving through the air
gravity
a 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 (projectile) after it is given an initial forward velocity
inertia
the tendency of an object to resist a change in its motion
mass
a measure of the inertia of an object and depends on the amount of matter the object contains
weight
the force of gravity acting on an object
momentum
the product of an object's mass and it's velocity
law of conservation of momentum
if no net forces act on a system, then the total momentum of the system does not change.
electromagnetic force
associated with charged particles. Electric force and magnetic force are the only forces that can both attract and repel
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
an attractive force that cacts only over a short range
gravitational force
an attractive force that acts between two masses
centripetal force
the center-directed force that contunuoulsy change the direction of an object to make it move in a circle
mass, distance
gravity increases as ___ is increased and ___ is decreased
9.8 m/s2
what is the acceleration due to gravity?
first
The state of motion of an object does not change as long as the net force acting on the object is zero. What law of Newton's is this?
acceleration=net force % mass
what is the equation for newton's second law?
weight= mass * acceleration
what is the formula for weight?
third
whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first object. what law is this?
momentum = mass * velocity
what is the equation for momentum?
speed, direction
a force can cause a resting object to move, or it can accelerate a moving object by changing the objects ___ or ____
balanced
when the net forces are ____, the net force is zero and there is no change in the object's motion
accelerates
when an unbalanced force actos on an object, the object ____
static, sliding, rolling, fluid
what are the four types of friction? (greatest to lowest)
gravity
Earth's ___ acts downward toward the center of Earth
gravity, air resistance
___ causes objects to accelerate downward, whereas ___ acts in the direction opposite to the motion and reduces acceleration
initial forward velocity, downward vertical force
the combination of an _____ and the ____ of gravity causes the ball to follow a curved path
both
two coins are knocked off a table at the same time by different forces. Which coin will hit the floor first?
momentum
an object has a large ____ if the product of its mass and velocity is large
closed system
in a _____, the loss of momentum of one object equals the gain in momentum of another object-momentum is conserved
electric, magnetic
____ force and ___force are the only forces that can both attract and repel
strong, weak
two forces, the ___ nuclear force and the __ nuclear force, act within the nucleus to hold it together
law of universal gravitation
Newton's _________ states that every object in the universe attracts every other object
accels
the more the force the greater objects ____
motion
when you change an unbalanced force, you can change an object's ____
speed
when you change a object's magnitude, you change the object's ____
spring scale
what scale measures how much things weigh? in newtons
acceleration
a change in velocity and direction causes a change in what?
friction
___moves in the opposite direction
strength
what's another word for magnitude?
unbalanced force
an ___ is a forcfe that results when the net force acting on an object is not equal to zero
electromagnetic, strong nuclear, weak nuclear, gravitational
what are the four main universal forces?