physics exam 1

kinetic energy=

1/2 mass X speed2

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

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

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

principle of flotation

a floating object displaces a weight of fluid equal to its own weight

hang from a pair of gym rings and the upward support forces of the rings will always

add up to equal your weight

water pressure is greatest against

all sides of a submerged object

for the astronauts inside the orbiting space shuttle, there is no force of earth's gravity acting on them. this statement is

always false

archimedes' principle

an immersed body is buoyed up by a force equal to the weight of the fluid it displaces

projectile

any object that is projected and continues in motion by its own inertia

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

earth satellites are typically more than 100 km high so as to be above the earth's

atmosphere

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

impulse=

change in momentum

acceleration=

change of velocity/time of interval

a rock is thrown upward at 50e with respect to the horizontal. as it rises, its vertical component of velocity

decreases

kinetic energy

depends on the mass on the object as well as its speed

the two measurements necessary for calculating average speed

distance and time

the two measurements necessary for calculating average speed are

distance and time

speed=

distance covered/travel time

an object is propelled along a straight-line path by a force. if the net force were doubled, its acceleration would

double

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

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

EF=0

equilibrium rule. E "the vector sum of." F stands for forces. vector quantities are equal to zero

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

universal gravitation constant

f=g m1m2/d2

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

work=

force X distance

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

pressure=

force/area

law of universal gravitation

force~ m1m2/d2

the scientist to first introduce the concept of inertia

galileo

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

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

if a nonrotating object has no acceleration, then we can say for certain that it is

in mechanical equilibrium

law of conservation of momentum

in the absence of an external force, the momentum of a system remains unchanged

barometer

instrument used to measure the pressure of the atmosphere

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

a force is a vector quantity because it has both

magnitude and direction

two quantities necessary for a vector quantity

magnitude and direction

an object maintains its state of motion because it has

mass

kilogram is a measure of

mass

momentum=

mass X speed when direction is not important

momentum=

mass X velocity

density=

mass/volume

density

measure of compactness

what does an object have when moving that it doesn't have when at rest

momentum

objects that have zero acceleration

objects moving at constant velocity, at rest, and in mechanical equilibrium

if you push for an hour against a stationary wall, you do no work

on the wall

boyle's law

p1v1=p2v2

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

mass

quantity of matter in an object

a rock is thrown upward at 50 degrees with respect to the horizontal. as it rises, its horizontal component of velocity

remains unchanged

newton discovered

that gravity is universal

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

potential energy

the energy that is stored and held in readiness

support force is called normal force because

the force acts at right angles to the surface

weight

the force upon an object due to gravity

your weight is

the gravitational attraction between you and the earth

galileo's concept of inertia

the name given to the property by which objects resist which objects resist changes in motion is friction

inelastic collision

the objects stick together

which of the following has the largest momentum relative to earth

the pickup truck speeding along the highway

inertia

the property by which objects resist changes in motion

energy

the property of a system that enables it to do work

the difference between impulse and impact force involves the

time the force acts

if you push an object just as far while applying twice the force, you do

twice as much work

if you do work on an object in half the time, your power output is

twice the usual power output

when a chocolate bar is cut in half, its density is

unchanged

buoyant force

upward force

efficiency=

useful energy output/total energy input

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

difference between velocity and acceleration

velocity is speed and direction of the object and acceleration is moving things that undergo variations in motion

gravitational potential energy=

weight X height

liquid pressure=

weight density X depth

atmospheric pressure

weight of air

weight density=

weight/volume

elastic collision

when a ball moves and hits another ball and then it stops while the other ball begins to move

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

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

bernoulli's principle

where the speed of a fluid increases, internal pressure in the fluid decreases

power=

work done/time interval

work energy theorem

work=change in kinetic energy

a force required to maintain an object at a constant velocity in free space is equal to

zero