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Gravity
Terms in this set (123)
Motion
An object's change in position relative to a reference point.
Frame of Reference
a system for specifying the precise location of objects in space and time
Average Speed
total distance divided by total time
Instantaneous Speed
the speed of an object at one instant of time
Velocity
Speed in a given direction
Acceleration
The rate at which velocity changes
Free Fall
the motion of a falling object when the only force acting on it is gravity
Vectors
quantities that have both a magnitude and a direction
Scalars
quantities that are fully described by a magnitude (or numerical value) alone
Vectors Addition
the process of finding the geometric sum of a number of vectors by repeated application of the parallelogram law.
Components of Vectors
the projections of a vector along the axes of a coordinate system
Projectile Motion
the curved path that an object follows when thrown, launched, or otherwise projected near the surface of Earth
Horizontal Velocity
velocity parallel to Earth's surface
Vertical Velocity
speed that changes as it travels in projectile motion
Newton's First Law of Motion
an object in motion will remain in motion unless acted upon by another force
Newton's Second Law of Motion
The acceleration of an object depends on the mass of the object and the amount of force applied.
Newton's Third Law of Motion
For every action there is an equal and opposite reaction
Force
A push or a pull
Friction
A force that opposes motion between two surfaces that are in contact
Mass
the amount of matter in an object
Weight
A measure of the force of gravity on an object
Volume
The amount of space an object takes up
Net Force
The combination of all forces acting on an object
Balanced Forces
Equal forces acting on an object in opposite directions
Unbalanced Forces
Forces that produce a nonzero net force, which changes an object's motion
Terminal Velocity
the constant velocity of a falling object when the force of air resistance is equal in magnitude and opposite in direction to the force of gravity
Pressure
Force per unit area.
Momentum
mass x velocity
Law of Conservation of Momentum
The rule that in the absence of outside forces the total momentum of objects that interact does not change.
Elastic Collisions
A collision in which no kinetic energy is lost; gas particles have same speed before and after the collision
Inelastic Collisions
Objects collide and become altered and generate heat during the collision.
Work
force x distance
Energy
the ability to do work
Kinetic Energy
energy of motion
Potential Energy
stored energy
Power
the rate at which work is done
Mechanical Energy
Kinetic or potential energy associated with the motion or position of an object
Law of Conservation of Energy
Energy cannot be created or destroyed
Angle of incidence
the angle between the incident ray and the normal
Angle of reflection
The angle between the reflected ray and the normal
Law of reflection
the angle of incidence is equal to the angle of reflection
Normal
A line perpendicular to a surface
Reflection
The bouncing back of a wave when it hits a surface through which it cannot pass.
Refraction
The bending of a wave as it passes at an angle from one medium to another
Converging lens
lens such that a beam of light passing through it is brought to a point or focus
Diverging lens
a lens that is thinnest in the middle causing light rays to spread apart
Focal length
the distance from the center of a lens to the focal point
Focal point
The center of interest on a page or set of facing pages, created by using color, contrast and proportion.
Lens
the transparent structure behind the pupil that changes shape to help focus images on the retina
Ray diagram
shows how rays change direction when they strike mirrors and pass through lenses
Real image
a copy of an object formed at the point where light rays actually meet
Virtual image
a reflected optical image (as seen in a plane mirror)
Farsighted
a condition in which faraway objects are seen more clearly than near objects because the image of near objects is focused behind the retina
Nearsighted
a condition in which nearby objects are seen more clearly than distant objects because distant objects focus in front of the retina
10
The SI is based on units of
derived
A unit of measurement that is obtained by combining other units is a _______unit.
200 cm3
The volume of an object measuring 20 cm length, 2.5 cm width, and 4 cm height would be
21m/s
What is the speed of a car that travels 84 meters in 4 seconds?
rate of change of velocity
Acceleration is the
5 m/s2
A car accelerates from 5 m/s to 30 m/s in 5 seconds. What is its acceleration?
d
Suppose you are in a car that is going around a curve. The speedometer reads a constant speed 45 miles per hour. Which of the following is NOT true?
a. You and your car are accelerating. b. You speed is constant.
c. Your direction is constantly changing. d. Your velocity is constant.
current
The flow of charged particles in wires, motors, light bulbs and others devices is called electric:
speed, volume, mass, temperature, power, energy, and time
what are examples of scalars?
distance, displacement, speed, velocity, acceleration, force, mass, momentum, energy, work, and power
what are examples of vectors?
is on
A closed circuit:
opposes the motion of an object
Friction is a force that
pull of gravity on an object
Weight is a measure of the
continue to move in a straight line
A car is traveling at 90 km/h when it suddenly stops. The passenger in the car will
the same
Compared to its mass on Earth, the mass of a-10 kg object on the moon is
does not change
When forces are balanced, the motion of an object
3 m/s2
A girl pulls on a 15-kg wagon with a constant force of 45 N. What is the wagon acceleration?
force per unit area
Pressure is defined as
0.5 amps
A stereo receiver is plugged into a 120-volt outlet. If the receiver has a resistance of 240 ohms, how much current does it use?
road
A force is exerted on the tires of a car to accelerate the car along the road. The force is exerted by the
distance
Work is force times
600 J
The amount of work done when a force of 300 N moves an object a distance of 2 m is
1 g/cm3
A block of wood 3 cm on each side has a mass of 27 g. What is density of this block?
divided by time
Power equals work
weight and height
Gravitational potential energy depends on
0
The amount of work done by two boys who each apply 200 N of force in an unsuccessful attempt to move a stalled car is
increases by nine times
When car speed triples, its kinetic energy
moving
An object that has kinetic energy must be
three times the work
Raising an auto in a service station requires work. Raising it three times as high requires
energy
An object at rest may have
1200 joules
What is the work done in lifting 60 kg of blocks to a height of 20 m?
12 J
A 6 kg object moves at 2 m/s. Its kinetic energy is
atomic number
All atoms of the same element have the same
isotopes
Atoms of the same element that have the same number of protons but different number of neutrons are called
compound
A substance made from atoms of different elements that are combined in a fixed proportion is called
liquid
Matter that has a definite volume but no shape is a
mass divided by volume
Density is defined as
unchanged
When solid block is cut in half, its density is
2 N
Suppose a stone weighs 10 N in the air, but in water weighs only 8 N. What is the buoyant force acting on the stone?
you and the jacket together have density less than your density alone
The reason a life jacket helps you float is that
momentum
Inertia in motion.
law of conservation of momentum
In an absence of a net external force, the momentum of an object or system of objects
is unchanged.
newton's second law
F = ma
air bags
Decrease the force of impact in a collision
seat belts
Protect passengers from the effects of inertia.
impact
If the change in momentum occurs over a short time, the force of ______ is large.
newton's third law
To every action there is always an equal and opposing reaction.
inelastic collision
Transfer of energy through motion.
power
The rate in which work is done.
energy
The ability to cause change.
matter and energy
physics is the study of....
1000
kilo means...
1/100 (0.01)
centi means...
1/1000 (0.001)
milli means...
the ideas of physics extend into more complex sciences
physics is the most basic science because...
celsius
temperature of most laboratory thermometers
earth
the most common frame of reference is...
constant speed
A distance-time graph is a straight line for
less
Compared to its weight on Earth, a 50-kg object on the moon will weigh
motion when a balanced force acts on an object
Newton's first law describes
second law
Motion when an unbalanced force acts on an object is described by Newton's
f=ma
The equation that correctly expresses Newton's second law is:
third law
"Forces occur in pairs" is another way of stating Newton's:
288 k
A temperature of 150C is equivalent to:
a result of adding one neutron, one proton, and one electron
A quanta is best described as:
0 k
The temperature at which molecules in a substance have the lowest amount of energy possible is :
solid
matter with definite shape and definite volume
gas
matter with no definite shape or volume
plasma
most common form of visible matter in the universe
;