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86 terms

physics exam 1

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kilogram is a measure of
mass
objects that have zero acceleration
objects moving at constant velocity, at rest, and in mechanical equilibrium
hang from a pair of gym rings and the upward support forces of the rings will always
add up to equal your weight
the two measurements necessary for calculating average speed
distance and time
if a freely falling object were somehow equipped with an odometer to measure the distance it travels, then the amount of distance it travels each succeeding second would be
greater than the second before
an object maintains its state of motion because it has
mass
a force is a vector quantity because it has both
magnitude and direction
a force required to maintain an object at a constant velocity in free space is equal to
zero
a player hits a ball with a bat. the action force is the impact of the bat against the ball. the action to this force is the
force of the ball against the bat
which of the following has the largest momentum relative to earth
the pickup truck speeding along the highway
if you push an object just as far while applying twice the force, you do
twice as much work
what does an object have when moving that it doesn't have when at rest
momentum
newton discovered
that gravity is universal
for the astronauts inside the orbiting space shuttle, there is no force of earth's gravity acting on them. this statement is
always false
a rock is thrown upward at 50e with respect to the horizontal. as it rises, its vertical component of velocity
decreases
earth satellites are typically more than 100 km high so as to be above the earth's
atmosphere
water pressure is greatest against
all sides of a submerged object
the impulse-momentum relationship and example
impulse is equal to the change in momentum. when a golfer is about to hit the ball, zero force is exerted until contact. when contact arrives, there is an increase in momentum due to the impulse
newton's first law of motion
every object continues in a state of rest or of uniform speed in a straight line unless acted upon by a nonzero force. inertia
newton's second law of motion
the acceleration produced by net force is directly proportional to the net force, is in the same direction as the net force, and is inversely proportional to the mass of the object. force of hand accelerates brick
newton's third law of motion
whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first. earth pulls on ball and ball pulls on earth
difference between velocity and acceleration
velocity is speed and direction of the object and acceleration is moving things that undergo variations in motion
the scientist to first introduce the concept of inertia
galileo
your weight is
the gravitational attraction between you and the earth
an object is pulled northward with a force of 10 N and southward with a force of 15 N. The magnitude of the net force on the object is
5 N
the two measurements necessary for calculating average speed are
distance and time
if a nonrotating object has no acceleration, then we can say for certain that it is
in mechanical equilibrium
whirl a rock at the end of a string and it follows a circular path. string breaks, the tendency of the rock is to
follow a straight-line path
an object is propelled along a straight-line path by a force. if the net force were doubled, its acceleration would
double
an object is in free-fall. at one instant, it travels at a speed of 50 m/s. exactly 1s later, its speed is about
60 m/s
an archer shoots an arrow. consider the action force to be the bowstring against the arrow. the reaction to this force is the
arrow's push against the bowstring
a freight train rolls along a track with considerable momentum. if it rolls at the same speed but has twice as much mass, its momentum
doubled
the difference between impulse and impact force involves the
time the force acts
a cannon recoils from firing a cannonball. the speed of the cannon's recoil is small because the
cannon has more mass than the ball
if you push for an hour against a stationary wall, you do no work
on the wall
what does an object have when moving that it doesn't have when at rest
momentum
if you do work on an object in half the time, your power output is
twice the usual power output
newton discovered
that gravity is universal
if your mass, the mass of the earth, and the mass of everything in the solar system were twice as much as it is now, yet everything stayed the same size, your weight on earth would
quadruple
a rock is thrown upward at 50 degrees with respect to the horizontal. as it rises, its horizontal component of velocity
remains unchanged
when a chocolate bar is cut in half, its density is
unchanged
galileo's concept of inertia
the name given to the property by which objects resist which objects resist changes in motion is friction
two quantities necessary for a vector quantity
magnitude and direction
support force is called normal force because
the force acts at right angles to the surface
the direction of friction compares with the velocity of a sliding object because
when you push hard enough on sliding furniture to match the friction, the net force is zero and it slides at constant velocity
is velocity is a vector? is speed?
velocity is a vector and speed is not because constant velocity means constant speed and constant direction. constant speed merely means steady speed. vector quantities specify direction and magnitudes and velocity does this, not speed
speed=
distance covered/travel time
acceleration=
change of velocity/time of interval
mass
quantity of matter in an object
weight
the force upon an object due to gravity
EF=0
equilibrium rule. E "the vector sum of." F stands for forces. vector quantities are equal to zero
inertia
the property by which objects resist changes in motion
momentum=
mass X velocity
momentum=
mass X speed when direction is not important
impulse=
change in momentum
law of conservation of momentum
in the absence of an external force, the momentum of a system remains unchanged
elastic collision
when a ball moves and hits another ball and then it stops while the other ball begins to move
inelastic collision
the objects stick together
work=
force X distance
energy
the property of a system that enables it to do work
potential energy
the energy that is stored and held in readiness
gravitational potential energy=
weight X height
kinetic energy
depends on the mass on the object as well as its speed
kinetic energy=
1/2 mass X speed2
work energy theorem
work=change in kinetic energy
law of conservation of energy
energy cannot be created or destroyed; it may be transformed from one form into another, but the total amount of energy never changes
power=
work done/time interval
efficiency=
useful energy output/total energy input
law of universal gravitation
force~ m1m2/d2
universal gravitation constant
f=g m1m2/d2
inverse square law
intensity of an effect from a localized source spreads uniformly throughout the surrounding space and weakens with the inverse square of the distance
inverse square law
intensity=1/distance2
projectile
any object that is projected and continues in motion by its own inertia
density=
mass/volume
density
measure of compactness
weight density=
weight/volume
pressure=
force/area
buoyant force
upward force
liquid pressure=
weight density X depth
archimedes' principle
an immersed body is buoyed up by a force equal to the weight of the fluid it displaces
principle of flotation
a floating object displaces a weight of fluid equal to its own weight
boyle's law
p1v1=p2v2
atmospheric pressure
weight of air
barometer
instrument used to measure the pressure of the atmosphere
pascal's principle
a change in pressure at any point in an enclosed fluid at rest is transmitted undiminished to all points in the fluid
bernoulli's principle
where the speed of a fluid increases, internal pressure in the fluid decreases